diff --git a/src/uvw/dns.cpp b/src/uvw/dns.cpp
index 1f22caf6..2a6b5536 100644
--- a/src/uvw/dns.cpp
+++ b/src/uvw/dns.cpp
@@ -49,32 +49,32 @@ UVW_INLINE auto GetAddrInfoReq::nodeAddrInfoSync(const char *node, const char *s
 }
 
 
-UVW_INLINE void GetAddrInfoReq::nodeAddrInfo(std::string node, addrinfo *hints) {
+UVW_INLINE void GetAddrInfoReq::nodeAddrInfo(const std::string &node, addrinfo *hints) {
     nodeAddrInfo(node.data(), nullptr, hints);
 }
 
 
-UVW_INLINE std::pair<bool, std::unique_ptr<addrinfo, GetAddrInfoReq::Deleter>> GetAddrInfoReq::nodeAddrInfoSync(std::string node, addrinfo *hints) {
+UVW_INLINE std::pair<bool, std::unique_ptr<addrinfo, GetAddrInfoReq::Deleter>> GetAddrInfoReq::nodeAddrInfoSync(const std::string &node, addrinfo *hints) {
     return nodeAddrInfoSync(node.data(), nullptr, hints);
 }
 
 
-UVW_INLINE void GetAddrInfoReq::serviceAddrInfo(std::string service, addrinfo *hints) {
+UVW_INLINE void GetAddrInfoReq::serviceAddrInfo(const std::string &service, addrinfo *hints) {
     nodeAddrInfo(nullptr, service.data(), hints);
 }
 
 
-UVW_INLINE std::pair<bool, std::unique_ptr<addrinfo, GetAddrInfoReq::Deleter>> GetAddrInfoReq::serviceAddrInfoSync(std::string service, addrinfo *hints) {
+UVW_INLINE std::pair<bool, std::unique_ptr<addrinfo, GetAddrInfoReq::Deleter>> GetAddrInfoReq::serviceAddrInfoSync(const std::string &service, addrinfo *hints) {
     return nodeAddrInfoSync(nullptr, service.data(), hints);
 }
 
 
-UVW_INLINE void GetAddrInfoReq::addrInfo(std::string node, std::string service, addrinfo *hints) {
+UVW_INLINE void GetAddrInfoReq::addrInfo(const std::string &node, const std::string &service, addrinfo *hints) {
     nodeAddrInfo(node.data(), service.data(), hints);
 }
 
 
-UVW_INLINE std::pair<bool, std::unique_ptr<addrinfo, GetAddrInfoReq::Deleter>> GetAddrInfoReq::addrInfoSync(std::string node, std::string service, addrinfo *hints) {
+UVW_INLINE std::pair<bool, std::unique_ptr<addrinfo, GetAddrInfoReq::Deleter>> GetAddrInfoReq::addrInfoSync(const std::string &node, const std::string &service, addrinfo *hints) {
     return nodeAddrInfoSync(node.data(), service.data(), hints);
 }
 
@@ -96,7 +96,7 @@ UVW_INLINE void GetNameInfoReq::nameInfo(const sockaddr &addr, int flags) {
 
 
 template<typename I>
-UVW_INLINE void GetNameInfoReq::nameInfo(std::string ip, unsigned int port, int flags) {
+UVW_INLINE void GetNameInfoReq::nameInfo(const std::string &ip, unsigned int port, int flags) {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
     nameInfo(reinterpret_cast<const sockaddr &>(addr), flags);
@@ -115,7 +115,7 @@ UVW_INLINE std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq
 
 
 template<typename I>
-UVW_INLINE std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync(std::string ip, unsigned int port, int flags) {
+UVW_INLINE std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync(const std::string &ip, unsigned int port, int flags) {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
     return nameInfoSync(reinterpret_cast<const sockaddr &>(addr), flags);
@@ -130,17 +130,18 @@ UVW_INLINE std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq
 
 // explicit instantiations
 #ifdef UVW_AS_LIB
-template void GetNameInfoReq::nameInfo<IPv4>(std::string ip, unsigned int port, int flags);
-template void GetNameInfoReq::nameInfo<IPv6>(std::string ip, unsigned int port, int flags);
+template void GetNameInfoReq::nameInfo<IPv4>(const std::string &, unsigned int, int);
+template void GetNameInfoReq::nameInfo<IPv6>(const std::string &, unsigned int, int);
 
-template void GetNameInfoReq::nameInfo<IPv4>(Addr addr, int flags);
-template void GetNameInfoReq::nameInfo<IPv6>(Addr addr, int flags);
+template void GetNameInfoReq::nameInfo<IPv4>(Addr, int);
+template void GetNameInfoReq::nameInfo<IPv6>(Addr, int);
 
-template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv4>(std::string ip, unsigned int port, int flags);
-template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv6>(std::string ip, unsigned int port, int flags);
+template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv4>(const std::string &, unsigned int, int);
+template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv6>(const std::string &, unsigned int, int);
 
-template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv4>(Addr addr, int flags);
-template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv6>(Addr addr, int flags);
+template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv4>(Addr, int);
+template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv6>(Addr, int);
 #endif // UVW_AS_LIB
 
+
 }
diff --git a/src/uvw/dns.h b/src/uvw/dns.h
index 1800f898..ef5f05fa 100644
--- a/src/uvw/dns.h
+++ b/src/uvw/dns.h
@@ -84,7 +84,7 @@ public:
      * @param hints Optional `addrinfo` data structure with additional address
      * type constraints.
      */
-    void nodeAddrInfo(std::string node, addrinfo *hints = nullptr);
+    void nodeAddrInfo(const std::string &node, addrinfo *hints = nullptr);
 
     /**
      * @brief Sync [getaddrinfo](http://linux.die.net/man/3/getaddrinfo).
@@ -97,7 +97,7 @@ public:
      * * A boolean value that is true in case of success, false otherwise.
      * * A `std::unique_ptr<addrinfo, Deleter>` containing the data requested.
      */
-    std::pair<bool, std::unique_ptr<addrinfo, Deleter>> nodeAddrInfoSync(std::string node, addrinfo *hints = nullptr);
+    std::pair<bool, std::unique_ptr<addrinfo, Deleter>> nodeAddrInfoSync(const std::string &node, addrinfo *hints = nullptr);
 
     /**
      * @brief Async [getaddrinfo](http://linux.die.net/man/3/getaddrinfo).
@@ -105,7 +105,7 @@ public:
      * @param hints Optional `addrinfo` data structure with additional address
      * type constraints.
      */
-    void serviceAddrInfo(std::string service, addrinfo *hints = nullptr);
+    void serviceAddrInfo(const std::string &service, addrinfo *hints = nullptr);
 
     /**
      * @brief Sync [getaddrinfo](http://linux.die.net/man/3/getaddrinfo).
@@ -118,7 +118,7 @@ public:
      * * A boolean value that is true in case of success, false otherwise.
      * * A `std::unique_ptr<addrinfo, Deleter>` containing the data requested.
      */
-    std::pair<bool, std::unique_ptr<addrinfo, Deleter>> serviceAddrInfoSync(std::string service, addrinfo *hints = nullptr);
+    std::pair<bool, std::unique_ptr<addrinfo, Deleter>> serviceAddrInfoSync(const std::string &service, addrinfo *hints = nullptr);
 
     /**
      * @brief Async [getaddrinfo](http://linux.die.net/man/3/getaddrinfo).
@@ -127,7 +127,7 @@ public:
      * @param hints Optional `addrinfo` data structure with additional address
      * type constraints.
      */
-    void addrInfo(std::string node, std::string service, addrinfo *hints = nullptr);
+    void addrInfo(const std::string &node, const std::string &service, addrinfo *hints = nullptr);
 
     /**
      * @brief Sync [getaddrinfo](http://linux.die.net/man/3/getaddrinfo).
@@ -141,7 +141,7 @@ public:
      * * A boolean value that is true in case of success, false otherwise.
      * * A `std::unique_ptr<addrinfo, Deleter>` containing the data requested.
      */
-    std::pair<bool, std::unique_ptr<addrinfo, Deleter>> addrInfoSync(std::string node, std::string service, addrinfo *hints = nullptr);
+    std::pair<bool, std::unique_ptr<addrinfo, Deleter>> addrInfoSync(const std::string &node, const std::string &service, addrinfo *hints = nullptr);
 };
 
 
@@ -173,7 +173,7 @@ public:
      * @param flags Optional flags that modify the behavior of `getnameinfo`.
      */
     template<typename I = IPv4>
-    void nameInfo(std::string ip, unsigned int port, int flags = 0);
+    void nameInfo(const std::string &ip, unsigned int port, int flags = 0);
 
     /**
      * @brief Async [getnameinfo](http://linux.die.net/man/3/getnameinfo).
@@ -211,7 +211,7 @@ public:
      *   * A `const char *` containing a valid service name.
      */
     template<typename I = IPv4>
-    std::pair<bool, std::pair<const char *, const char *>> nameInfoSync(std::string ip, unsigned int port, int flags = 0);
+    std::pair<bool, std::pair<const char *, const char *>> nameInfoSync(const std::string &ip, unsigned int port, int flags = 0);
 
     /**
      * @brief Sync [getnameinfo](http://linux.die.net/man/3/getnameinfo).
@@ -238,19 +238,20 @@ public:
 
 // (extern) explicit instantiations
 #ifdef UVW_AS_LIB
-extern template void GetNameInfoReq::nameInfo<IPv4>(std::string ip, unsigned int port, int flags);
-extern template void GetNameInfoReq::nameInfo<IPv6>(std::string ip, unsigned int port, int flags);
+extern template void GetNameInfoReq::nameInfo<IPv4>(const std::string &, unsigned int, int);
+extern template void GetNameInfoReq::nameInfo<IPv6>(const std::string &, unsigned int, int);
 
-extern template void GetNameInfoReq::nameInfo<IPv4>(Addr addr, int flags);
-extern template void GetNameInfoReq::nameInfo<IPv6>(Addr addr, int flags);
+extern template void GetNameInfoReq::nameInfo<IPv4>(Addr, int);
+extern template void GetNameInfoReq::nameInfo<IPv6>(Addr, int);
 
-extern template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv4>(std::string ip, unsigned int port, int flags);
-extern template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv6>(std::string ip, unsigned int port, int flags);
+extern template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv4>(const std::string &, unsigned int, int);
+extern template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv6>(const std::string &, unsigned int, int);
 
-extern template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv4>(Addr addr, int flags);
-extern template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv6>(Addr addr, int flags);
+extern template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv4>(Addr, int);
+extern template std::pair<bool, std::pair<const char *, const char *>> GetNameInfoReq::nameInfoSync<IPv6>(Addr, int);
 #endif // UVW_AS_LIB
 
+
 /**
  * Internal details not to be documented.
  * @endcond
@@ -264,4 +265,5 @@ extern template std::pair<bool, std::pair<const char *, const char *>> GetNameIn
 #include "dns.cpp"
 #endif
 
+
 #endif // UVW_DNS_INCLUDE_H
diff --git a/src/uvw/fs.cpp b/src/uvw/fs.cpp
index 5eae12b6..4a4c5ac8 100644
--- a/src/uvw/fs.cpp
+++ b/src/uvw/fs.cpp
@@ -66,12 +66,12 @@ UVW_INLINE bool FileReq::closeSync() {
 }
 
 
-UVW_INLINE void FileReq::open(std::string path, Flags<FileOpen> flags, int mode) {
+UVW_INLINE void FileReq::open(const std::string &path, Flags<FileOpen> flags, int mode) {
     cleanupAndInvoke(&uv_fs_open, parent(), get(), path.data(), flags, mode, &fsOpenCallback);
 }
 
 
-UVW_INLINE bool FileReq::openSync(std::string path, Flags<FileOpen> flags, int mode) {
+UVW_INLINE bool FileReq::openSync(const std::string &path, Flags<FileOpen> flags, int mode) {
     auto req = get();
 
     cleanupAndInvokeSync(&uv_fs_open, parent(), req, path.data(), flags, mode);
@@ -256,48 +256,48 @@ UVW_INLINE FsReq::~FsReq() noexcept {
 }
 
 
-UVW_INLINE void FsReq::unlink(std::string path) {
+UVW_INLINE void FsReq::unlink(const std::string &path) {
     cleanupAndInvoke(&uv_fs_unlink, parent(), get(), path.data(), &fsGenericCallback<Type::UNLINK>);
 }
 
 
-UVW_INLINE bool FsReq::unlinkSync(std::string path) {
+UVW_INLINE bool FsReq::unlinkSync(const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_unlink, parent(), req, path.data());
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::mkdir(std::string path, int mode) {
+UVW_INLINE void FsReq::mkdir(const std::string &path, int mode) {
     cleanupAndInvoke(&uv_fs_mkdir, parent(), get(), path.data(), mode, &fsGenericCallback<Type::MKDIR>);
 }
 
 
-UVW_INLINE bool FsReq::mkdirSync(std::string path, int mode) {
+UVW_INLINE bool FsReq::mkdirSync(const std::string &path, int mode) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_mkdir, parent(), req, path.data(), mode);
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::mkdtemp(std::string tpl) {
+UVW_INLINE void FsReq::mkdtemp(const std::string &tpl) {
     cleanupAndInvoke(&uv_fs_mkdtemp, parent(), get(), tpl.data(), &fsGenericCallback<Type::MKDTEMP>);
 }
 
 
-UVW_INLINE std::pair<bool, const char *> FsReq::mkdtempSync(std::string tpl) {
+UVW_INLINE std::pair<bool, const char *> FsReq::mkdtempSync(const std::string &tpl) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_mkdtemp, parent(), req, tpl.data());
     return std::make_pair(!(req->result < 0), req->path);
 }
 
 
-UVW_INLINE void FsReq::mkstemp(std::string tpl) {
+UVW_INLINE void FsReq::mkstemp(const std::string &tpl) {
     cleanupAndInvoke(&uv_fs_mkstemp, parent(), get(), tpl.data(), &fsResultCallback<Type::MKSTEMP>);
 }
 
 
-UVW_INLINE std::pair<bool, std::pair<std::string, std::size_t>> FsReq::mkstempSync(std::string tpl) {
+UVW_INLINE std::pair<bool, std::pair<std::string, std::size_t>> FsReq::mkstempSync(const std::string &tpl) {
     std::pair<bool, std::pair<std::string, std::size_t>> ret{false, {}};
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_mkdtemp, parent(), req, tpl.data());
@@ -312,36 +312,36 @@ UVW_INLINE std::pair<bool, std::pair<std::string, std::size_t>> FsReq::mkstempSy
 }
 
 
-UVW_INLINE void FsReq::lutime(std::string path, Time atime, Time mtime) {
+UVW_INLINE void FsReq::lutime(const std::string &path, Time atime, Time mtime) {
     cleanupAndInvoke(&uv_fs_lutime, parent(), get(), path.data(), atime.count(), mtime.count(), &fsGenericCallback<Type::LUTIME>);
 }
 
 
-UVW_INLINE bool FsReq::lutimeSync(std::string path, Time atime, Time mtime) {
+UVW_INLINE bool FsReq::lutimeSync(const std::string &path, Time atime, Time mtime) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_lutime, parent(), req, path.data(), atime.count(), mtime.count());
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::rmdir(std::string path) {
+UVW_INLINE void FsReq::rmdir(const std::string &path) {
     cleanupAndInvoke(&uv_fs_rmdir, parent(), get(), path.data(), &fsGenericCallback<Type::RMDIR>);
 }
 
 
-UVW_INLINE bool FsReq::rmdirSync(std::string path) {
+UVW_INLINE bool FsReq::rmdirSync(const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_rmdir, parent(), req, path.data());
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::scandir(std::string path, int flags) {
+UVW_INLINE void FsReq::scandir(const std::string &path, int flags) {
     cleanupAndInvoke(&uv_fs_scandir, parent(), get(), path.data(), flags, &fsResultCallback<Type::SCANDIR>);
 }
 
 
-UVW_INLINE std::pair<bool, std::size_t> FsReq::scandirSync(std::string path, int flags) {
+UVW_INLINE std::pair<bool, std::size_t> FsReq::scandirSync(const std::string &path, int flags) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_scandir, parent(), req, path.data(), flags);
     bool err = req->result < 0;
@@ -366,132 +366,132 @@ UVW_INLINE std::pair<bool, std::pair<FsReq::EntryType, const char *>> FsReq::sca
 }
 
 
-UVW_INLINE void FsReq::stat(std::string path) {
+UVW_INLINE void FsReq::stat(const std::string &path) {
     cleanupAndInvoke(&uv_fs_stat, parent(), get(), path.data(), &fsStatCallback<Type::STAT>);
 }
 
 
-UVW_INLINE std::pair<bool, Stat> FsReq::statSync(std::string path) {
+UVW_INLINE std::pair<bool, Stat> FsReq::statSync(const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_stat, parent(), req, path.data());
     return std::make_pair(!(req->result < 0), req->statbuf);
 }
 
 
-UVW_INLINE void FsReq::lstat(std::string path) {
+UVW_INLINE void FsReq::lstat(const std::string &path) {
     cleanupAndInvoke(&uv_fs_lstat, parent(), get(), path.data(), &fsStatCallback<Type::LSTAT>);
 }
 
 
-UVW_INLINE std::pair<bool, Stat> FsReq::lstatSync(std::string path) {
+UVW_INLINE std::pair<bool, Stat> FsReq::lstatSync(const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_lstat, parent(), req, path.data());
     return std::make_pair(!(req->result < 0), req->statbuf);
 }
 
 
-UVW_INLINE void FsReq::statfs(std::string path) {
+UVW_INLINE void FsReq::statfs(const std::string &path) {
     cleanupAndInvoke(&uv_fs_statfs, parent(), get(), path.data(), &fsStatfsCallback);
 }
 
 
-UVW_INLINE std::pair<bool, Statfs> FsReq::statfsSync(std::string path) {
+UVW_INLINE std::pair<bool, Statfs> FsReq::statfsSync(const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_statfs, parent(), req, path.data());
     return std::make_pair(!(req->result < 0), *static_cast<uv_statfs_t *>(req->ptr));
 }
 
 
-UVW_INLINE void FsReq::rename(std::string old, std::string path) {
+UVW_INLINE void FsReq::rename(const std::string &old, const std::string &path) {
     cleanupAndInvoke(&uv_fs_rename, parent(), get(), old.data(), path.data(), &fsGenericCallback<Type::RENAME>);
 }
 
 
-UVW_INLINE bool FsReq::renameSync(std::string old, std::string path) {
+UVW_INLINE bool FsReq::renameSync(const std::string &old, const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_rename, parent(), req, old.data(), path.data());
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::copyfile(std::string old, std::string path, Flags<CopyFile> flags) {
+UVW_INLINE void FsReq::copyfile(const std::string &old, const std::string &path, Flags<CopyFile> flags) {
     cleanupAndInvoke(&uv_fs_copyfile, parent(), get(), old.data(), path.data(), flags, &fsGenericCallback<Type::COPYFILE>);
 }
 
 
-UVW_INLINE bool FsReq::copyfileSync(std::string old, std::string path, Flags<CopyFile> flags) {
+UVW_INLINE bool FsReq::copyfileSync(const std::string &old, const std::string &path, Flags<CopyFile> flags) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_copyfile, parent(), get(), old.data(), path.data(), flags);
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::access(std::string path, int mode) {
+UVW_INLINE void FsReq::access(const std::string &path, int mode) {
     cleanupAndInvoke(&uv_fs_access, parent(), get(), path.data(), mode, &fsGenericCallback<Type::ACCESS>);
 }
 
 
-UVW_INLINE bool FsReq::accessSync(std::string path, int mode) {
+UVW_INLINE bool FsReq::accessSync(const std::string &path, int mode) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_access, parent(), req, path.data(), mode);
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::chmod(std::string path, int mode) {
+UVW_INLINE void FsReq::chmod(const std::string &path, int mode) {
     cleanupAndInvoke(&uv_fs_chmod, parent(), get(), path.data(), mode, &fsGenericCallback<Type::CHMOD>);
 }
 
 
-UVW_INLINE bool FsReq::chmodSync(std::string path, int mode) {
+UVW_INLINE bool FsReq::chmodSync(const std::string &path, int mode) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_chmod, parent(), req, path.data(), mode);
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::utime(std::string path, FsRequest::Time atime, FsRequest::Time mtime) {
+UVW_INLINE void FsReq::utime(const std::string &path, FsRequest::Time atime, FsRequest::Time mtime) {
     cleanupAndInvoke(&uv_fs_utime, parent(), get(), path.data(), atime.count(), mtime.count(), &fsGenericCallback<Type::UTIME>);
 }
 
 
-UVW_INLINE bool FsReq::utimeSync(std::string path, FsRequest::Time atime, FsRequest::Time mtime) {
+UVW_INLINE bool FsReq::utimeSync(const std::string &path, FsRequest::Time atime, FsRequest::Time mtime) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_utime, parent(), req, path.data(), atime.count(), mtime.count());
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::link(std::string old, std::string path) {
+UVW_INLINE void FsReq::link(const std::string &old, const std::string &path) {
     cleanupAndInvoke(&uv_fs_link, parent(), get(), old.data(), path.data(), &fsGenericCallback<Type::LINK>);
 }
 
 
-UVW_INLINE bool FsReq::linkSync(std::string old, std::string path) {
+UVW_INLINE bool FsReq::linkSync(const std::string &old, const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_link, parent(), req, old.data(), path.data());
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::symlink(std::string old, std::string path, Flags<SymLink> flags) {
+UVW_INLINE void FsReq::symlink(const std::string &old, const std::string &path, Flags<SymLink> flags) {
     cleanupAndInvoke(&uv_fs_symlink, parent(), get(), old.data(), path.data(), flags, &fsGenericCallback<Type::SYMLINK>);
 }
 
 
-UVW_INLINE bool FsReq::symlinkSync(std::string old, std::string path, Flags<SymLink> flags) {
+UVW_INLINE bool FsReq::symlinkSync(const std::string &old, const std::string &path, Flags<SymLink> flags) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_symlink, parent(), req, old.data(), path.data(), flags);
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::readlink(std::string path) {
+UVW_INLINE void FsReq::readlink(const std::string &path) {
     cleanupAndInvoke(&uv_fs_readlink, parent(), get(), path.data(), &fsReadlinkCallback);
 }
 
 
-UVW_INLINE std::pair<bool, std::pair<const char *, std::size_t>> FsReq::readlinkSync(std::string path) {
+UVW_INLINE std::pair<bool, std::pair<const char *, std::size_t>> FsReq::readlinkSync(const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_readlink, parent(), req, path.data());
     bool err = req->result < 0;
@@ -499,48 +499,48 @@ UVW_INLINE std::pair<bool, std::pair<const char *, std::size_t>> FsReq::readlink
 }
 
 
-UVW_INLINE void FsReq::realpath(std::string path) {
+UVW_INLINE void FsReq::realpath(const std::string &path) {
     cleanupAndInvoke(&uv_fs_realpath, parent(), get(), path.data(), &fsGenericCallback<Type::REALPATH>);
 }
 
 
-UVW_INLINE std::pair<bool, const char *> FsReq::realpathSync(std::string path) {
+UVW_INLINE std::pair<bool, const char *> FsReq::realpathSync(const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_realpath, parent(), req, path.data());
     return std::make_pair(!(req->result < 0), req->path);
 }
 
 
-UVW_INLINE void FsReq::chown(std::string path, Uid uid, Gid gid) {
+UVW_INLINE void FsReq::chown(const std::string &path, Uid uid, Gid gid) {
     cleanupAndInvoke(&uv_fs_chown, parent(), get(), path.data(), uid, gid, &fsGenericCallback<Type::CHOWN>);
 }
 
 
-UVW_INLINE bool FsReq::chownSync(std::string path, Uid uid, Gid gid) {
+UVW_INLINE bool FsReq::chownSync(const std::string &path, Uid uid, Gid gid) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_chown, parent(), req, path.data(), uid, gid);
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::lchown(std::string path, Uid uid, Gid gid) {
+UVW_INLINE void FsReq::lchown(const std::string &path, Uid uid, Gid gid) {
     cleanupAndInvoke(&uv_fs_lchown, parent(), get(), path.data(), uid, gid, &fsGenericCallback<Type::LCHOWN>);
 }
 
 
-UVW_INLINE bool FsReq::lchownSync(std::string path, Uid uid, Gid gid) {
+UVW_INLINE bool FsReq::lchownSync(const std::string &path, Uid uid, Gid gid) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_lchown, parent(), req, path.data(), uid, gid);
     return !(req->result < 0);
 }
 
 
-UVW_INLINE void FsReq::opendir(std::string path) {
+UVW_INLINE void FsReq::opendir(const std::string &path) {
     cleanupAndInvoke(&uv_fs_opendir, parent(), get(), path.data(), &fsGenericCallback<Type::OPENDIR>);
 }
 
 
-UVW_INLINE bool FsReq::opendirSync(std::string path) {
+UVW_INLINE bool FsReq::opendirSync(const std::string &path) {
     auto req = get();
     cleanupAndInvokeSync(&uv_fs_opendir, parent(), req, path.data());
     return !(req->result < 0);
diff --git a/src/uvw/fs.h b/src/uvw/fs.h
index c4af1d4a..799b5626 100644
--- a/src/uvw/fs.h
+++ b/src/uvw/fs.h
@@ -500,7 +500,7 @@ public:
      * @param flags Flags made out of underlying constants.
      * @param mode Mode, as described in the official documentation.
      */
-    void open(std::string path, Flags<FileOpen> flags, int mode);
+    void open(const std::string &path, Flags<FileOpen> flags, int mode);
 
     /**
      * @brief Sync [open](http://linux.die.net/man/2/open).
@@ -539,7 +539,7 @@ public:
      * @param mode Mode, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool openSync(std::string path, Flags<FileOpen> flags, int mode);
+    bool openSync(const std::string &path, Flags<FileOpen> flags, int mode);
 
     /**
      * @brief Async [read](http://linux.die.net/man/2/preadv).
@@ -804,14 +804,14 @@ public:
      *
      * @param path Path, as described in the official documentation.
      */
-    void unlink(std::string path);
+    void unlink(const std::string &path);
 
     /**
      * @brief Sync [unlink](http://linux.die.net/man/2/unlink).
      * @param path Path, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool unlinkSync(std::string path);
+    bool unlinkSync(const std::string &path);
 
     /**
      * @brief Async [mkdir](http://linux.die.net/man/2/mkdir).
@@ -822,7 +822,7 @@ public:
      * @param path Path, as described in the official documentation.
      * @param mode Mode, as described in the official documentation.
      */
-    void mkdir(std::string path, int mode);
+    void mkdir(const std::string &path, int mode);
 
     /**
      * @brief Sync [mkdir](http://linux.die.net/man/2/mkdir).
@@ -830,7 +830,7 @@ public:
      * @param mode Mode, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool mkdirSync(std::string path, int mode);
+    bool mkdirSync(const std::string &path, int mode);
 
     /**
      * @brief Async [mktemp](http://linux.die.net/man/3/mkdtemp).
@@ -840,7 +840,7 @@ public:
      *
      * @param tpl Template, as described in the official documentation.
      */
-    void mkdtemp(std::string tpl);
+    void mkdtemp(const std::string &tpl);
 
     /**
      * @brief Sync [mktemp](http://linux.die.net/man/3/mkdtemp).
@@ -851,7 +851,7 @@ public:
      * * A boolean value that is true in case of success, false otherwise.
      * * The actual path of the newly created directory.
      */
-    std::pair<bool, const char *> mkdtempSync(std::string tpl);
+    std::pair<bool, const char *> mkdtempSync(const std::string &tpl);
 
     /**
      * @brief Async [mkstemp](https://linux.die.net/man/3/mkstemp).
@@ -861,7 +861,7 @@ public:
      *
      * @param tpl Template, as described in the official documentation.
      */
-    void mkstemp(std::string tpl);
+    void mkstemp(const std::string &tpl);
 
     /**
      * @brief Sync [mkstemp](https://linux.die.net/man/3/mkstemp).
@@ -883,7 +883,7 @@ public:
      * false otherwise.
      * * The second parameter is a composed value (see above).
      */
-    std::pair<bool, std::pair<std::string, std::size_t>> mkstempSync(std::string tpl);
+    std::pair<bool, std::pair<std::string, std::size_t>> mkstempSync(const std::string &tpl);
 
     /**
      * @brief Async [lutime](http://linux.die.net/man/3/lutimes).
@@ -897,7 +897,7 @@ public:
      * @param mtime `std::chrono::duration<double>`, having the same meaning as
      * described in the official documentation.
      */
-    void lutime(std::string path, Time atime, Time mtime);
+    void lutime(const std::string &path, Time atime, Time mtime);
 
     /**
      * @brief Sync [lutime](http://linux.die.net/man/3/lutimes).
@@ -908,7 +908,7 @@ public:
      * described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool lutimeSync(std::string path, Time atime, Time mtime);
+    bool lutimeSync(const std::string &path, Time atime, Time mtime);
 
     /**
      * @brief Async [rmdir](http://linux.die.net/man/2/rmdir).
@@ -918,14 +918,14 @@ public:
      *
      * @param path Path, as described in the official documentation.
      */
-    void rmdir(std::string path);
+    void rmdir(const std::string &path);
 
     /**
      * @brief Sync [rmdir](http://linux.die.net/man/2/rmdir).
      * @param path Path, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool rmdirSync(std::string path);
+    bool rmdirSync(const std::string &path);
 
     /**
      * @brief Async [scandir](http://linux.die.net/man/3/scandir).
@@ -936,7 +936,7 @@ public:
      * @param path Path, as described in the official documentation.
      * @param flags Flags, as described in the official documentation.
      */
-    void scandir(std::string path, int flags);
+    void scandir(const std::string &path, int flags);
 
     /**
      * @brief Sync [scandir](http://linux.die.net/man/3/scandir).
@@ -948,7 +948,7 @@ public:
      * * A boolean value that is true in case of success, false otherwise.
      * * The number of directory entries selected.
      */
-    std::pair<bool, std::size_t> scandirSync(std::string path, int flags);
+    std::pair<bool, std::size_t> scandirSync(const std::string &path, int flags);
 
     /**
      * @brief Gets entries populated with the next directory entry data.
@@ -989,7 +989,7 @@ public:
      *
      * @param path Path, as described in the official documentation.
      */
-    void stat(std::string path);
+    void stat(const std::string &path);
 
     /**
      * @brief Sync [stat](http://linux.die.net/man/2/stat).
@@ -1000,7 +1000,7 @@ public:
      * * A boolean value that is true in case of success, false otherwise.
      * * An initialized instance of Stat.
      */
-    std::pair<bool, Stat> statSync(std::string path);
+    std::pair<bool, Stat> statSync(const std::string &path);
 
     /**
      * @brief Async [lstat](http://linux.die.net/man/2/lstat).
@@ -1010,7 +1010,7 @@ public:
      *
      * @param path Path, as described in the official documentation.
      */
-    void lstat(std::string path);
+    void lstat(const std::string &path);
 
     /**
      * @brief Sync [lstat](http://linux.die.net/man/2/lstat).
@@ -1021,7 +1021,7 @@ public:
      * * A boolean value that is true in case of success, false otherwise.
      * * An initialized instance of Stat.
      */
-    std::pair<bool, Stat> lstatSync(std::string path);
+    std::pair<bool, Stat> lstatSync(const std::string &path);
 
     /**
      * @brief Async [statfs](http://linux.die.net/man/2/statfs).
@@ -1034,7 +1034,7 @@ public:
      *
      * @param path Path, as described in the official documentation.
      */
-    void statfs(std::string path);
+    void statfs(const std::string &path);
 
     /**
      * @brief Sync [statfs](http://linux.die.net/man/2/statfs).
@@ -1048,7 +1048,7 @@ public:
      * * A boolean value that is true in case of success, false otherwise.
      * * An initialized instance of Statfs.
      */
-    std::pair<bool, Statfs> statfsSync(std::string path);
+    std::pair<bool, Statfs> statfsSync(const std::string &path);
 
     /**
      * @brief Async [rename](http://linux.die.net/man/2/rename).
@@ -1059,7 +1059,7 @@ public:
      * @param old Old path, as described in the official documentation.
      * @param path New path, as described in the official documentation.
      */
-    void rename(std::string old, std::string path);
+    void rename(const std::string &old, const std::string &path);
 
     /**
      * @brief Sync [rename](http://linux.die.net/man/2/rename).
@@ -1067,7 +1067,7 @@ public:
      * @param path New path, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool renameSync(std::string old, std::string path);
+    bool renameSync(const std::string &old, const std::string &path);
 
     /**
      * @brief Copies a file asynchronously from a path to a new one.
@@ -1098,7 +1098,7 @@ public:
      * @param path New path, as described in the official documentation.
      * @param flags Optional additional flags.
      */
-    void copyfile(std::string old, std::string path, Flags<CopyFile> flags = Flags<CopyFile>{});
+    void copyfile(const std::string &old, const std::string &path, Flags<CopyFile> flags = Flags<CopyFile>{});
 
     /**
      * @brief Copies a file synchronously from a path to a new one.
@@ -1119,7 +1119,7 @@ public:
      * @param flags Optional additional flags.
      * @return True in case of success, false otherwise.
      */
-    bool copyfileSync(std::string old, std::string path, Flags<CopyFile> flags = Flags<CopyFile>{});
+    bool copyfileSync(const std::string &old, const std::string &path, Flags<CopyFile> flags = Flags<CopyFile>{});
 
     /**
      * @brief Async [access](http://linux.die.net/man/2/access).
@@ -1130,7 +1130,7 @@ public:
      * @param path Path, as described in the official documentation.
      * @param mode Mode, as described in the official documentation.
      */
-    void access(std::string path, int mode);
+    void access(const std::string &path, int mode);
 
     /**
      * @brief Sync [access](http://linux.die.net/man/2/access).
@@ -1138,7 +1138,7 @@ public:
      * @param mode Mode, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool accessSync(std::string path, int mode);
+    bool accessSync(const std::string &path, int mode);
 
     /**
      * @brief Async [chmod](http://linux.die.net/man/2/chmod).
@@ -1149,7 +1149,7 @@ public:
      * @param path Path, as described in the official documentation.
      * @param mode Mode, as described in the official documentation.
      */
-    void chmod(std::string path, int mode);
+    void chmod(const std::string &path, int mode);
 
     /**
      * @brief Sync [chmod](http://linux.die.net/man/2/chmod).
@@ -1157,7 +1157,7 @@ public:
      * @param mode Mode, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool chmodSync(std::string path, int mode);
+    bool chmodSync(const std::string &path, int mode);
 
     /**
      * @brief Async [utime](http://linux.die.net/man/2/utime).
@@ -1171,7 +1171,7 @@ public:
      * @param mtime `std::chrono::duration<double>`, having the same meaning as
      * described in the official documentation.
      */
-    void utime(std::string path, Time atime, Time mtime);
+    void utime(const std::string &path, Time atime, Time mtime);
 
     /**
      * @brief Sync [utime](http://linux.die.net/man/2/utime).
@@ -1182,7 +1182,7 @@ public:
      * described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool utimeSync(std::string path, Time atime, Time mtime);
+    bool utimeSync(const std::string &path, Time atime, Time mtime);
 
     /**
      * @brief Async [link](http://linux.die.net/man/2/link).
@@ -1193,7 +1193,7 @@ public:
      * @param old Old path, as described in the official documentation.
      * @param path New path, as described in the official documentation.
      */
-    void link(std::string old, std::string path);
+    void link(const std::string &old, const std::string &path);
 
     /**
      * @brief Sync [link](http://linux.die.net/man/2/link).
@@ -1201,7 +1201,7 @@ public:
      * @param path New path, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool linkSync(std::string old, std::string path);
+    bool linkSync(const std::string &old, const std::string &path);
 
     /**
      * @brief Async [symlink](http://linux.die.net/man/2/symlink).
@@ -1220,7 +1220,7 @@ public:
      * @param path New path, as described in the official documentation.
      * @param flags Optional additional flags.
      */
-    void symlink(std::string old, std::string path, Flags<SymLink> flags = Flags<SymLink>{});
+    void symlink(const std::string &old, const std::string &path, Flags<SymLink> flags = Flags<SymLink>{});
 
     /**
      * @brief Sync [symlink](http://linux.die.net/man/2/symlink).
@@ -1237,7 +1237,7 @@ public:
      * @param flags Flags, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool symlinkSync(std::string old, std::string path, Flags<SymLink> flags = Flags<SymLink>{});
+    bool symlinkSync(const std::string &old, const std::string &path, Flags<SymLink> flags = Flags<SymLink>{});
 
     /**
      * @brief Async [readlink](http://linux.die.net/man/2/readlink).
@@ -1247,7 +1247,7 @@ public:
      *
      * @param path Path, as described in the official documentation.
      */
-    void readlink(std::string path);
+    void readlink(const std::string &path);
 
     /**
      * @brief Sync [readlink](http://linux.die.net/man/2/readlink).
@@ -1260,7 +1260,7 @@ public:
      *   * A bunch of data read from the given path.
      *   * The amount of data read from the given path.
      */
-    std::pair<bool, std::pair<const char *, std::size_t>> readlinkSync(std::string path);
+    std::pair<bool, std::pair<const char *, std::size_t>> readlinkSync(const std::string &path);
 
     /**
      * @brief Async [realpath](http://linux.die.net/man/3/realpath).
@@ -1270,7 +1270,7 @@ public:
      *
      * @param path Path, as described in the official documentation.
      */
-    void realpath(std::string path);
+    void realpath(const std::string &path);
 
     /**
      * @brief Sync [realpath](http://linux.die.net/man/3/realpath).
@@ -1281,7 +1281,7 @@ public:
      * * A boolean value that is true in case of success, false otherwise.
      * * The canonicalized absolute pathname.
      */
-    std::pair<bool, const char *> realpathSync(std::string path);
+    std::pair<bool, const char *> realpathSync(const std::string &path);
 
     /**
      * @brief Async [chown](http://linux.die.net/man/2/chown).
@@ -1293,7 +1293,7 @@ public:
      * @param uid UID, as described in the official documentation.
      * @param gid GID, as described in the official documentation.
      */
-    void chown(std::string path, Uid uid, Gid gid);
+    void chown(const std::string &path, Uid uid, Gid gid);
 
     /**
      * @brief Sync [chown](http://linux.die.net/man/2/chown).
@@ -1302,7 +1302,7 @@ public:
      * @param gid GID, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool chownSync(std::string path, Uid uid, Gid gid);
+    bool chownSync(const std::string &path, Uid uid, Gid gid);
 
     /**
      * @brief Async [lchown](https://linux.die.net/man/2/lchown).
@@ -1314,7 +1314,7 @@ public:
      * @param uid UID, as described in the official documentation.
      * @param gid GID, as described in the official documentation.
      */
-    void lchown(std::string path, Uid uid, Gid gid);
+    void lchown(const std::string &path, Uid uid, Gid gid);
 
     /**
      * @brief Sync [lchown](https://linux.die.net/man/2/lchown).
@@ -1323,7 +1323,7 @@ public:
      * @param gid GID, as described in the official documentation.
      * @return True in case of success, false otherwise.
      */
-    bool lchownSync(std::string path, Uid uid, Gid gid);
+    bool lchownSync(const std::string &path, Uid uid, Gid gid);
 
     /**
      * @brief Opens a path asynchronously as a directory stream.
@@ -1337,7 +1337,7 @@ public:
      *
      * @param path The path to open as a directory stream.
      */
-    void opendir(std::string path);
+    void opendir(const std::string &path);
 
     /**
      * @brief Opens a path synchronously as a directory stream.
@@ -1349,7 +1349,7 @@ public:
      * @param path The path to open as a directory stream.
      * @return True in case of success, false otherwise.
      */
-    bool opendirSync(std::string path);
+    bool opendirSync(const std::string &path);
 
     /**
      * @brief Closes asynchronously a directory stream.
@@ -1459,4 +1459,5 @@ struct FsHelper {
 #include "fs.cpp"
 #endif
 
+
 #endif // UVW_FS_INCLUDE_H
diff --git a/src/uvw/fs_event.cpp b/src/uvw/fs_event.cpp
index 65ed0208..85e428f3 100644
--- a/src/uvw/fs_event.cpp
+++ b/src/uvw/fs_event.cpp
@@ -3,7 +3,6 @@
 #endif
 
 #include <utility>
-
 #include "config.h"
 
 
@@ -31,12 +30,12 @@ UVW_INLINE bool FsEventHandle::init() {
 }
 
 
-UVW_INLINE void FsEventHandle::start(std::string path, Flags<Event> flags) {
+UVW_INLINE void FsEventHandle::start(const std::string &path, Flags<Event> flags) {
     invoke(&uv_fs_event_start, get(), &startCallback, path.data(), flags);
 }
 
 
-UVW_INLINE void FsEventHandle::start(std::string path, FsEventHandle::Event flag) {
+UVW_INLINE void FsEventHandle::start(const std::string &path, FsEventHandle::Event flag) {
     start(std::move(path), Flags<Event>{flag});
 }
 
diff --git a/src/uvw/fs_event.h b/src/uvw/fs_event.h
index 6cbc5a08..7d2ab41c 100644
--- a/src/uvw/fs_event.h
+++ b/src/uvw/fs_event.h
@@ -105,7 +105,7 @@ public:
      * @param path The file or directory to be monitored.
      * @param flags Additional flags to control the behavior.
      */
-    void start(std::string path, Flags<Event> flags = Flags<Event>{});
+    void start(const std::string &path, Flags<Event> flags = Flags<Event>{});
 
     /**
      * @brief Starts watching the specified path.
@@ -124,7 +124,7 @@ public:
      * @param path The file or directory to be monitored.
      * @param flag Additional flag to control the behavior.
      */
-    void start(std::string path, Event flag);
+    void start(const std::string &path, Event flag);
 
     /**
      * @brief Stops polling the file descriptor.
@@ -146,4 +146,5 @@ public:
 #include "fs_event.cpp"
 #endif
 
+
 #endif // UVW_FS_EVENT_INCLUDE_H
diff --git a/src/uvw/fs_poll.cpp b/src/uvw/fs_poll.cpp
index f5cdbb97..885ecbe2 100644
--- a/src/uvw/fs_poll.cpp
+++ b/src/uvw/fs_poll.cpp
@@ -31,7 +31,7 @@ UVW_INLINE bool FsPollHandle::init() {
 }
 
 
-UVW_INLINE void FsPollHandle::start(std::string file, FsPollHandle::Time interval) {
+UVW_INLINE void FsPollHandle::start(const std::string &file, FsPollHandle::Time interval) {
     invoke(&uv_fs_poll_start, get(), &startCallback, file.data(), interval.count());
 }
 
diff --git a/src/uvw/fs_poll.h b/src/uvw/fs_poll.h
index a264eb3b..f914b506 100644
--- a/src/uvw/fs_poll.h
+++ b/src/uvw/fs_poll.h
@@ -57,7 +57,7 @@ public:
      * @param file The path to the file to be checked.
      * @param interval Milliseconds between successive checks.
      */
-    void start(std::string file, Time interval);
+    void start(const std::string &file, Time interval);
 
     /**
      * @brief Stops the handle.
@@ -80,4 +80,5 @@ public:
 #include "fs_poll.cpp"
 #endif
 
+
 #endif // UVW_FS_POLL_INCLUDE_H
diff --git a/src/uvw/lib.cpp b/src/uvw/lib.cpp
index 44308ed1..5df54489 100644
--- a/src/uvw/lib.cpp
+++ b/src/uvw/lib.cpp
@@ -10,7 +10,7 @@
 namespace uvw {
 
 
-UVW_INLINE SharedLib::SharedLib(UnderlyingType<SharedLib, uv_lib_t>::ConstructorAccess ca, std::shared_ptr<Loop> ref, std::string filename) noexcept
+UVW_INLINE SharedLib::SharedLib(UnderlyingType<SharedLib, uv_lib_t>::ConstructorAccess ca, std::shared_ptr<Loop> ref, const std::string &filename) noexcept
     : UnderlyingType{ca, std::move(ref)}
 {
     opened = (0 == uv_dlopen(filename.data(), get()));
diff --git a/src/uvw/lib.h b/src/uvw/lib.h
index 7e8fff18..8c951316 100644
--- a/src/uvw/lib.h
+++ b/src/uvw/lib.h
@@ -21,7 +21,7 @@ namespace uvw {
  */
 class SharedLib final: public UnderlyingType<SharedLib, uv_lib_t> {
 public:
-    explicit SharedLib(ConstructorAccess ca, std::shared_ptr<Loop> ref, std::string filename) noexcept;
+    explicit SharedLib(ConstructorAccess ca, std::shared_ptr<Loop> ref, const std::string &filename) noexcept;
 
     ~SharedLib() noexcept;
 
@@ -41,7 +41,7 @@ public:
      * @return A valid function pointer in case of success, `nullptr` otherwise.
      */
     template<typename F>
-    F * sym(std::string name) {
+    F * sym(const std::string &name) {
         static_assert(std::is_function_v<F>);
         F *func;
         auto err = uv_dlsym(get(), name.data(), reinterpret_cast<void**>(&func));
@@ -67,4 +67,5 @@ private:
 #include "lib.cpp"
 #endif
 
+
 #endif // UVW_LIB_INCLUDE_H
diff --git a/src/uvw/pipe.cpp b/src/uvw/pipe.cpp
index bad31511..b6933367 100644
--- a/src/uvw/pipe.cpp
+++ b/src/uvw/pipe.cpp
@@ -3,7 +3,6 @@
 #endif
 
 #include <utility>
-
 #include "config.h"
 
 
@@ -25,12 +24,12 @@ UVW_INLINE void PipeHandle::open(FileHandle file) {
 }
 
 
-UVW_INLINE void PipeHandle::bind(std::string name) {
+UVW_INLINE void PipeHandle::bind(const std::string &name) {
     invoke(&uv_pipe_bind, get(), name.data());
 }
 
 
-UVW_INLINE void PipeHandle::connect(std::string name) {
+UVW_INLINE void PipeHandle::connect(const std::string &name) {
     auto listener = [ptr = shared_from_this()](const auto &event, const auto &) {
         ptr->publish(event);
     };
diff --git a/src/uvw/pipe.h b/src/uvw/pipe.h
index d37ea40a..576b2c88 100644
--- a/src/uvw/pipe.h
+++ b/src/uvw/pipe.h
@@ -69,7 +69,7 @@ public:
      *
      * @param name A valid file path.
      */
-    void bind(std::string name);
+    void bind(const std::string &name);
 
     /**
      * @brief Connects to the Unix domain socket or the named pipe.
@@ -81,7 +81,7 @@ public:
      *
      * @param name A valid domain socket or named pipe.
      */
-    void connect(std::string name);
+    void connect(const std::string &name);
 
     /**
      * @brief Gets the name of the Unix domain socket or the named pipe.
@@ -164,4 +164,5 @@ private:
 #include "pipe.cpp"
 #endif
 
+
 #endif // UVW_PIPE_INCLUDE_H
diff --git a/src/uvw/process.cpp b/src/uvw/process.cpp
index a416e0ef..49f4c04a 100644
--- a/src/uvw/process.cpp
+++ b/src/uvw/process.cpp
@@ -82,7 +82,7 @@ UVW_INLINE int ProcessHandle::pid() noexcept {
 }
 
 
-UVW_INLINE ProcessHandle &ProcessHandle::cwd(std::string path) noexcept {
+UVW_INLINE ProcessHandle &ProcessHandle::cwd(const std::string &path) noexcept {
     poCwd = path;
     return *this;
 }
diff --git a/src/uvw/process.h b/src/uvw/process.h
index f19fcc4d..ac9e852d 100644
--- a/src/uvw/process.h
+++ b/src/uvw/process.h
@@ -137,7 +137,7 @@ public:
      * @param path The working directory to be used when `spawn()` is invoked.
      * @return A reference to this process handle.
      */
-    ProcessHandle & cwd(std::string path) noexcept;
+    ProcessHandle & cwd(const std::string &path) noexcept;
 
     /**
      * @brief Sets flags that control how `spawn()` behaves.
@@ -251,4 +251,5 @@ private:
 #include "process.cpp"
 #endif
 
+
 #endif // UVW_PROCESS_INCLUDE_H
diff --git a/src/uvw/tcp.cpp b/src/uvw/tcp.cpp
index a1b0ec28..db6759c6 100644
--- a/src/uvw/tcp.cpp
+++ b/src/uvw/tcp.cpp
@@ -44,7 +44,7 @@ UVW_INLINE void TCPHandle::bind(const sockaddr &addr, Flags<Bind> opts) {
 
 
 template<typename I>
-UVW_INLINE void TCPHandle::bind(std::string ip, unsigned int port, Flags<Bind> opts)
+UVW_INLINE void TCPHandle::bind(const std::string &ip, unsigned int port, Flags<Bind> opts)
 {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
@@ -71,7 +71,7 @@ UVW_INLINE Addr TCPHandle::peer() const noexcept {
 
 
 template<typename I>
-UVW_INLINE void TCPHandle::connect(std::string ip, unsigned int port) {
+UVW_INLINE void TCPHandle::connect(const std::string &ip, unsigned int port) {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
     connect(reinterpret_cast<const sockaddr &>(addr));
@@ -103,8 +103,8 @@ UVW_INLINE void TCPHandle::closeReset() {
 
 // explicit instantiations
 #ifdef UVW_AS_LIB
-template void TCPHandle::bind<IPv4>(std::string, unsigned int, Flags<Bind>);
-template void TCPHandle::bind<IPv6>(std::string, unsigned int, Flags<Bind>);
+template void TCPHandle::bind<IPv4>(const std::string &, unsigned int, Flags<Bind>);
+template void TCPHandle::bind<IPv6>(const std::string &, unsigned int, Flags<Bind>);
 
 template void TCPHandle::bind<IPv4>(Addr, Flags<Bind>);
 template void TCPHandle::bind<IPv6>(Addr, Flags<Bind>);
@@ -115,11 +115,12 @@ template Addr TCPHandle::sock<IPv6>() const noexcept;
 template Addr TCPHandle::peer<IPv4>() const noexcept;
 template Addr TCPHandle::peer<IPv6>() const noexcept;
 
-template void TCPHandle::connect<IPv4>(std::string, unsigned int);
-template void TCPHandle::connect<IPv6>(std::string, unsigned int);
+template void TCPHandle::connect<IPv4>(const std::string &, unsigned int);
+template void TCPHandle::connect<IPv6>(const std::string &, unsigned int);
 
 template void TCPHandle::connect<IPv4>(Addr addr);
 template void TCPHandle::connect<IPv6>(Addr addr);
 #endif // UVW_AS_LIB
 
+
 }
diff --git a/src/uvw/tcp.h b/src/uvw/tcp.h
index cd023948..d5019090 100644
--- a/src/uvw/tcp.h
+++ b/src/uvw/tcp.h
@@ -136,7 +136,7 @@ public:
      * @param opts Optional additional flags.
      */
     template<typename I = IPv4>
-    void bind(std::string ip, unsigned int port, Flags<Bind> opts = Flags<Bind>{});
+    void bind(const std::string &ip, unsigned int port, Flags<Bind> opts = Flags<Bind>{});
 
     /**
      * @brief Binds the handle to an address and port.
@@ -197,7 +197,7 @@ public:
      * @param port The port to which to bind.
      */
     template<typename I = IPv4>
-    void connect(std::string ip, unsigned int port);
+    void connect(const std::string &ip, unsigned int port);
 
     /**
      * @brief Establishes an IPv4 or IPv6 TCP connection.
@@ -238,8 +238,8 @@ private:
 
 // (extern) explicit instantiations
 #ifdef UVW_AS_LIB
-extern template void TCPHandle::bind<IPv4>(std::string, unsigned int, Flags<Bind>);
-extern template void TCPHandle::bind<IPv6>(std::string, unsigned int, Flags<Bind>);
+extern template void TCPHandle::bind<IPv4>(const std::string &, unsigned int, Flags<Bind>);
+extern template void TCPHandle::bind<IPv6>(const std::string &, unsigned int, Flags<Bind>);
 
 extern template void TCPHandle::bind<IPv4>(Addr, Flags<Bind>);
 extern template void TCPHandle::bind<IPv6>(Addr, Flags<Bind>);
@@ -250,13 +250,14 @@ extern template Addr TCPHandle::sock<IPv6>() const noexcept;
 extern template Addr TCPHandle::peer<IPv4>() const noexcept;
 extern template Addr TCPHandle::peer<IPv6>() const noexcept;
 
-extern template void TCPHandle::connect<IPv4>(std::string, unsigned int);
-extern template void TCPHandle::connect<IPv6>(std::string, unsigned int);
+extern template void TCPHandle::connect<IPv4>(const std::string &, unsigned int);
+extern template void TCPHandle::connect<IPv6>(const std::string &, unsigned int);
 
 extern template void TCPHandle::connect<IPv4>(Addr addr);
 extern template void TCPHandle::connect<IPv6>(Addr addr);
 #endif // UVW_AS_LIB
 
+
 /**
  * Internal details not to be documented.
  * @endcond
@@ -270,4 +271,5 @@ extern template void TCPHandle::connect<IPv6>(Addr addr);
 #include "tcp.cpp"
 #endif
 
+
 #endif // UVW_TCP_INCLUDE_H
diff --git a/src/uvw/udp.cpp b/src/uvw/udp.cpp
index f68ce4b3..915b6b3a 100644
--- a/src/uvw/udp.cpp
+++ b/src/uvw/udp.cpp
@@ -51,7 +51,7 @@ UVW_INLINE void UDPHandle::connect(const sockaddr &addr) {
 
 
 template<typename I>
-UVW_INLINE void UDPHandle::connect(std::string ip, unsigned int port) {
+UVW_INLINE void UDPHandle::connect(const std::string &ip, unsigned int port) {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
     connect(reinterpret_cast<const sockaddr &>(addr));
@@ -76,7 +76,7 @@ UVW_INLINE Addr UDPHandle::peer() const noexcept {
 
 
 template<typename I>
-UVW_INLINE void UDPHandle::bind(std::string ip, unsigned int port, Flags<Bind> opts) {
+UVW_INLINE void UDPHandle::bind(const std::string &ip, unsigned int port, Flags<Bind> opts) {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
     bind(reinterpret_cast<const sockaddr &>(addr), std::move(opts));
@@ -96,7 +96,7 @@ UVW_INLINE Addr UDPHandle::sock() const noexcept {
 
 
 template<typename I>
-UVW_INLINE bool UDPHandle::multicastMembership(std::string multicast, std::string iface, Membership membership) {
+UVW_INLINE bool UDPHandle::multicastMembership(const std::string &multicast, const std::string &iface, Membership membership) {
     return (0 == uv_udp_set_membership(get(), multicast.data(), iface.data(), static_cast<uv_membership>(membership)));
 }
 
@@ -112,7 +112,7 @@ UVW_INLINE bool UDPHandle::multicastTtl(int val) {
 
 
 template<typename I>
-UVW_INLINE bool UDPHandle::multicastInterface(std::string iface) {
+UVW_INLINE bool UDPHandle::multicastInterface(const std::string &iface) {
     return (0 == uv_udp_set_multicast_interface(get(), iface.data()));
 }
 
@@ -144,7 +144,7 @@ UVW_INLINE void UDPHandle::send(const sockaddr &addr, std::unique_ptr<char[]> da
 
 
 template<typename I>
-UVW_INLINE void UDPHandle::send(std::string ip, unsigned int port, std::unique_ptr<char[]> data, unsigned int len) {
+UVW_INLINE void UDPHandle::send(const std::string &ip, unsigned int port, std::unique_ptr<char[]> data, unsigned int len) {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
     send(reinterpret_cast<const sockaddr &>(addr), std::move(data), len);
@@ -173,7 +173,7 @@ UVW_INLINE void UDPHandle::send(const sockaddr &addr, char *data, unsigned int l
 
 
 template<typename I>
-UVW_INLINE void UDPHandle::send(std::string ip, unsigned int port, char *data, unsigned int len) {
+UVW_INLINE void UDPHandle::send(const std::string &ip, unsigned int port, char *data, unsigned int len) {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
     send(reinterpret_cast<const sockaddr &>(addr), data, len);
@@ -201,7 +201,7 @@ UVW_INLINE int UDPHandle::trySend(const sockaddr &addr, std::unique_ptr<char[]>
 
 
 template<typename I>
-UVW_INLINE int UDPHandle::trySend(std::string ip, unsigned int port, std::unique_ptr<char[]> data, unsigned int len) {
+UVW_INLINE int UDPHandle::trySend(const std::string &ip, unsigned int port, std::unique_ptr<char[]> data, unsigned int len) {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
     return trySend(reinterpret_cast<const sockaddr &>(addr), std::move(data), len);
@@ -229,7 +229,7 @@ UVW_INLINE int UDPHandle::trySend(const sockaddr &addr, char *data, unsigned int
 
 
 template<typename I>
-UVW_INLINE int UDPHandle::trySend(std::string ip, unsigned int port, char *data, unsigned int len) {
+UVW_INLINE int UDPHandle::trySend(const std::string &ip, unsigned int port, char *data, unsigned int len) {
     typename details::IpTraits<I>::Type addr;
     details::IpTraits<I>::addrFunc(ip.data(), port, &addr);
     return trySend(reinterpret_cast<const sockaddr &>(addr), data, len);
@@ -265,8 +265,8 @@ UVW_INLINE size_t UDPHandle::sendQueueCount() const noexcept {
 
 // explicit instantiations
 #ifdef UVW_AS_LIB
-template void UDPHandle::connect<IPv4>(std::string, unsigned int);
-template void UDPHandle::connect<IPv6>(std::string, unsigned int);
+template void UDPHandle::connect<IPv4>(const std::string &, unsigned int);
+template void UDPHandle::connect<IPv6>(const std::string &, unsigned int);
 
 template void UDPHandle::connect<IPv4>(Addr);
 template void UDPHandle::connect<IPv6>(Addr);
@@ -274,8 +274,8 @@ template void UDPHandle::connect<IPv6>(Addr);
 template Addr UDPHandle::peer<IPv4>() const noexcept;
 template Addr UDPHandle::peer<IPv6>() const noexcept;
 
-template void UDPHandle::bind<IPv4>(std::string, unsigned int, Flags<Bind>);
-template void UDPHandle::bind<IPv6>(std::string, unsigned int, Flags<Bind>);
+template void UDPHandle::bind<IPv4>(const std::string &, unsigned int, Flags<Bind>);
+template void UDPHandle::bind<IPv6>(const std::string &, unsigned int, Flags<Bind>);
 
 template void UDPHandle::bind<IPv4>(Addr, Flags<Bind>);
 template void UDPHandle::bind<IPv6>(Addr, Flags<Bind>);
@@ -283,20 +283,20 @@ template void UDPHandle::bind<IPv6>(Addr, Flags<Bind>);
 template Addr UDPHandle::sock<IPv4>() const noexcept;
 template Addr UDPHandle::sock<IPv6>() const noexcept;
 
-template bool UDPHandle::multicastMembership<IPv4>(std::string, std::string, Membership);
-template bool UDPHandle::multicastMembership<IPv6>(std::string, std::string, Membership);
+template bool UDPHandle::multicastMembership<IPv4>(const std::string &, const std::string &, Membership);
+template bool UDPHandle::multicastMembership<IPv6>(const std::string &, const std::string &, Membership);
 
-template bool UDPHandle::multicastInterface<IPv4>(std::string);
-template bool UDPHandle::multicastInterface<IPv6>(std::string);
+template bool UDPHandle::multicastInterface<IPv4>(const std::string &);
+template bool UDPHandle::multicastInterface<IPv6>(const std::string &);
 
-template void UDPHandle::send<IPv4>(std::string, unsigned int, std::unique_ptr<char[]>, unsigned int);
-template void UDPHandle::send<IPv6>(std::string, unsigned int, std::unique_ptr<char[]>, unsigned int);
+template void UDPHandle::send<IPv4>(const std::string &, unsigned int, std::unique_ptr<char[]>, unsigned int);
+template void UDPHandle::send<IPv6>(const std::string &, unsigned int, std::unique_ptr<char[]>, unsigned int);
 
 template void UDPHandle::send<IPv4>(Addr, std::unique_ptr<char[]>, unsigned int);
 template void UDPHandle::send<IPv6>(Addr, std::unique_ptr<char[]>, unsigned int);
 
-template void UDPHandle::send<IPv4>(std::string, unsigned int, char *, unsigned int);
-template void UDPHandle::send<IPv6>(std::string, unsigned int, char *, unsigned int);
+template void UDPHandle::send<IPv4>(const std::string &, unsigned int, char *, unsigned int);
+template void UDPHandle::send<IPv6>(const std::string &, unsigned int, char *, unsigned int);
 
 template void UDPHandle::send<IPv4>(Addr, char *, unsigned int);
 template void UDPHandle::send<IPv6>(Addr, char *, unsigned int);
@@ -304,8 +304,8 @@ template void UDPHandle::send<IPv6>(Addr, char *, unsigned int);
 template int UDPHandle::trySend<IPv4>(const sockaddr &, std::unique_ptr<char[]>, unsigned int);
 template int UDPHandle::trySend<IPv6>(const sockaddr &, std::unique_ptr<char[]>, unsigned int);
 
-template int UDPHandle::trySend<IPv4>(std::string, unsigned int, std::unique_ptr<char[]>, unsigned int);
-template int UDPHandle::trySend<IPv6>(std::string, unsigned int, std::unique_ptr<char[]>, unsigned int);
+template int UDPHandle::trySend<IPv4>(const std::string &, unsigned int, std::unique_ptr<char[]>, unsigned int);
+template int UDPHandle::trySend<IPv6>(const std::string &, unsigned int, std::unique_ptr<char[]>, unsigned int);
 
 template int UDPHandle::trySend<IPv4>(Addr, std::unique_ptr<char[]>, unsigned int);
 template int UDPHandle::trySend<IPv6>(Addr, std::unique_ptr<char[]>, unsigned int);
@@ -313,8 +313,8 @@ template int UDPHandle::trySend<IPv6>(Addr, std::unique_ptr<char[]>, unsigned in
 template int UDPHandle::trySend<IPv4>(const sockaddr &, char *, unsigned int);
 template int UDPHandle::trySend<IPv6>(const sockaddr &, char *, unsigned int);
 
-template int UDPHandle::trySend<IPv4>(std::string, unsigned int, char *, unsigned int);
-template int UDPHandle::trySend<IPv6>(std::string, unsigned int, char *, unsigned int);
+template int UDPHandle::trySend<IPv4>(const std::string &, unsigned int, char *, unsigned int);
+template int UDPHandle::trySend<IPv6>(const std::string &, unsigned int, char *, unsigned int);
 
 template int UDPHandle::trySend<IPv4>(Addr, char *, unsigned int);
 template int UDPHandle::trySend<IPv6>(Addr, char *, unsigned int);
@@ -323,4 +323,5 @@ template void UDPHandle::recv<IPv4>();
 template void UDPHandle::recv<IPv6>();
 #endif // UVW_AS_LIB
 
+
 }
diff --git a/src/uvw/udp.h b/src/uvw/udp.h
index e4090a22..c250ecad 100644
--- a/src/uvw/udp.h
+++ b/src/uvw/udp.h
@@ -193,7 +193,7 @@ public:
      * @param port The port to which to bind.
      */
     template<typename I = IPv4>
-    void connect(std::string ip, unsigned int port);
+    void connect(const std::string &ip, unsigned int port);
 
     /**
      * @brief Associates the handle to a remote address and port (either IPv4 or
@@ -248,7 +248,7 @@ public:
      * @param opts Optional additional flags.
      */
     template<typename I = IPv4>
-    void bind(std::string ip, unsigned int port, Flags<Bind> opts = Flags<Bind>{});
+    void bind(const std::string &ip, unsigned int port, Flags<Bind> opts = Flags<Bind>{});
 
     /**
      * @brief Binds the UDP handle to an IP address and port.
@@ -293,7 +293,7 @@ public:
      * @return True in case of success, false otherwise.
      */
     template<typename I = IPv4>
-    bool multicastMembership(std::string multicast, std::string iface, Membership membership);
+    bool multicastMembership(const std::string &multicast, const std::string &iface, Membership membership);
 
     /**
      * @brief Sets IP multicast loop flag.
@@ -318,7 +318,7 @@ public:
      * @return True in case of success, false otherwise.
      */
     template<typename I = IPv4>
-    bool multicastInterface(std::string iface);
+    bool multicastInterface(const std::string &iface);
 
     /**
      * @brief Sets broadcast on or off.
@@ -372,7 +372,7 @@ public:
      * @param len The lenght of the submitted data.
      */
     template<typename I = IPv4>
-    void send(std::string ip, unsigned int port, std::unique_ptr<char[]> data, unsigned int len);
+    void send(const std::string &ip, unsigned int port, std::unique_ptr<char[]> data, unsigned int len);
 
     /**
      * @brief Sends data over the UDP socket.
@@ -432,7 +432,7 @@ public:
      * @param len The lenght of the submitted data.
      */
     template<typename I = IPv4>
-    void send(std::string ip, unsigned int port, char *data, unsigned int len);
+    void send(const std::string &ip, unsigned int port, char *data, unsigned int len);
 
     /**
      * @brief Sends data over the UDP socket.
@@ -481,7 +481,7 @@ public:
      * @return Number of bytes written.
      */
     template<typename I = IPv4>
-    int trySend(std::string ip, unsigned int port, std::unique_ptr<char[]> data, unsigned int len);
+    int trySend(const std::string &ip, unsigned int port, std::unique_ptr<char[]> data, unsigned int len);
 
     /**
      * @brief Sends data over the UDP socket.
@@ -524,7 +524,7 @@ public:
      * @return Number of bytes written.
      */
     template<typename I = IPv4>
-    int trySend(std::string ip, unsigned int port, char *data, unsigned int len);
+    int trySend(const std::string &ip, unsigned int port, char *data, unsigned int len);
 
     /**
      * @brief Sends data over the UDP socket.
@@ -587,8 +587,8 @@ private:
 
 // (extern) explicit instantiations
 #ifdef UVW_AS_LIB
-extern template void UDPHandle::connect<IPv4>(std::string, unsigned int);
-extern template void UDPHandle::connect<IPv6>(std::string, unsigned int);
+extern template void UDPHandle::connect<IPv4>(const std::string &, unsigned int);
+extern template void UDPHandle::connect<IPv6>(const std::string &, unsigned int);
 
 extern template void UDPHandle::connect<IPv4>(Addr);
 extern template void UDPHandle::connect<IPv6>(Addr);
@@ -596,8 +596,8 @@ extern template void UDPHandle::connect<IPv6>(Addr);
 extern template Addr UDPHandle::peer<IPv4>() const noexcept;
 extern template Addr UDPHandle::peer<IPv6>() const noexcept;
 
-extern template void UDPHandle::bind<IPv4>(std::string, unsigned int, Flags<Bind>);
-extern template void UDPHandle::bind<IPv6>(std::string, unsigned int, Flags<Bind>);
+extern template void UDPHandle::bind<IPv4>(const std::string &, unsigned int, Flags<Bind>);
+extern template void UDPHandle::bind<IPv6>(const std::string &, unsigned int, Flags<Bind>);
 
 extern template void UDPHandle::bind<IPv4>(Addr, Flags<Bind>);
 extern template void UDPHandle::bind<IPv6>(Addr, Flags<Bind>);
@@ -605,20 +605,20 @@ extern template void UDPHandle::bind<IPv6>(Addr, Flags<Bind>);
 extern template Addr UDPHandle::sock<IPv4>() const noexcept;
 extern template Addr UDPHandle::sock<IPv6>() const noexcept;
 
-extern template bool UDPHandle::multicastMembership<IPv4>(std::string, std::string, Membership);
-extern template bool UDPHandle::multicastMembership<IPv6>(std::string, std::string, Membership);
+extern template bool UDPHandle::multicastMembership<IPv4>(const std::string &, const std::string &, Membership);
+extern template bool UDPHandle::multicastMembership<IPv6>(const std::string &, const std::string &, Membership);
 
-extern template bool UDPHandle::multicastInterface<IPv4>(std::string);
-extern template bool UDPHandle::multicastInterface<IPv6>(std::string);
+extern template bool UDPHandle::multicastInterface<IPv4>(const std::string &);
+extern template bool UDPHandle::multicastInterface<IPv6>(const std::string &);
 
-extern template void UDPHandle::send<IPv4>(std::string, unsigned int, std::unique_ptr<char[]>, unsigned int);
-extern template void UDPHandle::send<IPv6>(std::string, unsigned int, std::unique_ptr<char[]>, unsigned int);
+extern template void UDPHandle::send<IPv4>(const std::string &, unsigned int, std::unique_ptr<char[]>, unsigned int);
+extern template void UDPHandle::send<IPv6>(const std::string &, unsigned int, std::unique_ptr<char[]>, unsigned int);
 
 extern template void UDPHandle::send<IPv4>(Addr, std::unique_ptr<char[]>, unsigned int);
 extern template void UDPHandle::send<IPv6>(Addr, std::unique_ptr<char[]>, unsigned int);
 
-extern template void UDPHandle::send<IPv4>(std::string, unsigned int, char *, unsigned int);
-extern template void UDPHandle::send<IPv6>(std::string, unsigned int, char *, unsigned int);
+extern template void UDPHandle::send<IPv4>(const std::string &, unsigned int, char *, unsigned int);
+extern template void UDPHandle::send<IPv6>(const std::string &, unsigned int, char *, unsigned int);
 
 extern template void UDPHandle::send<IPv4>(Addr, char *, unsigned int);
 extern template void UDPHandle::send<IPv6>(Addr, char *, unsigned int);
@@ -626,8 +626,8 @@ extern template void UDPHandle::send<IPv6>(Addr, char *, unsigned int);
 extern template int UDPHandle::trySend<IPv4>(const sockaddr &, std::unique_ptr<char[]>, unsigned int);
 extern template int UDPHandle::trySend<IPv6>(const sockaddr &, std::unique_ptr<char[]>, unsigned int);
 
-extern template int UDPHandle::trySend<IPv4>(std::string, unsigned int, std::unique_ptr<char[]>, unsigned int);
-extern template int UDPHandle::trySend<IPv6>(std::string, unsigned int, std::unique_ptr<char[]>, unsigned int);
+extern template int UDPHandle::trySend<IPv4>(const std::string &, unsigned int, std::unique_ptr<char[]>, unsigned int);
+extern template int UDPHandle::trySend<IPv6>(const std::string &, unsigned int, std::unique_ptr<char[]>, unsigned int);
 
 extern template int UDPHandle::trySend<IPv4>(Addr, std::unique_ptr<char[]>, unsigned int);
 extern template int UDPHandle::trySend<IPv6>(Addr, std::unique_ptr<char[]>, unsigned int);
@@ -635,8 +635,8 @@ extern template int UDPHandle::trySend<IPv6>(Addr, std::unique_ptr<char[]>, unsi
 extern template int UDPHandle::trySend<IPv4>(const sockaddr &, char *, unsigned int);
 extern template int UDPHandle::trySend<IPv6>(const sockaddr &, char *, unsigned int);
 
-extern template int UDPHandle::trySend<IPv4>(std::string, unsigned int, char *, unsigned int);
-extern template int UDPHandle::trySend<IPv6>(std::string, unsigned int, char *, unsigned int);
+extern template int UDPHandle::trySend<IPv4>(const std::string &, unsigned int, char *, unsigned int);
+extern template int UDPHandle::trySend<IPv6>(const std::string &, unsigned int, char *, unsigned int);
 
 extern template int UDPHandle::trySend<IPv4>(Addr, char *, unsigned int);
 extern template int UDPHandle::trySend<IPv6>(Addr, char *, unsigned int);
@@ -645,6 +645,7 @@ extern template void UDPHandle::recv<IPv4>();
 extern template void UDPHandle::recv<IPv6>();
 #endif // UVW_AS_LIB
 
+
 /**
  * Internal details not to be documented.
  * @endcond
@@ -658,4 +659,5 @@ extern template void UDPHandle::recv<IPv6>();
 #include "udp.cpp"
 #endif
 
+
 #endif // UVW_UDP_INCLUDE_H
diff --git a/src/uvw/util.cpp b/src/uvw/util.cpp
index 95ef3252..921ba221 100644
--- a/src/uvw/util.cpp
+++ b/src/uvw/util.cpp
@@ -278,7 +278,7 @@ UVW_INLINE std::string Utilities::processTitle() {
 }
 
 
-UVW_INLINE bool Utilities::processTitle(std::string title) {
+UVW_INLINE bool Utilities::processTitle(const std::string &title) {
     return (0 == uv_set_process_title(title.c_str()));
 }
 
diff --git a/src/uvw/util.h b/src/uvw/util.h
index 72c3ca31..3796fb19 100644
--- a/src/uvw/util.h
+++ b/src/uvw/util.h
@@ -742,7 +742,7 @@ struct Utilities {
      * @param title The process title to be set.
      * @return True in case of success, false otherwise.
      */
-    static bool processTitle(std::string title);
+    static bool processTitle(const std::string &title);
 
     /**
      * @brief Gets memory information (in bytes).
@@ -846,4 +846,5 @@ Overloaded(Func...) -> Overloaded<Func...>;
 #include "util.cpp"
 #endif
 
+
 #endif // UVW_UTIL_INCLUDE_H