diff --git a/lib/internal/js_stream_socket.js b/lib/internal/js_stream_socket.js
index ebe90cccc75f45..cdf6cd7ac7e5bd 100644
--- a/lib/internal/js_stream_socket.js
+++ b/lib/internal/js_stream_socket.js
@@ -157,6 +157,7 @@ class JSStreamSocket extends Socket {
     let pending = bufs.length;
 
     this.stream.cork();
+    // Use `var` over `let` for performance optimization.
     for (var i = 0; i < bufs.length; ++i)
       this.stream.write(bufs[i], done);
     this.stream.uncork();