[perf] Optimize buffer copy in readBufferLengthEncodedCopy with subarray

Author: rusher

lib/io/packet.js

@@ -233,9 +233,9 @@ class Packet {
 
   readBufferLengthEncodedCopy() {
     const len = this.readUnsignedLength();
-    if (len === null) return null;    
+    if (len === null) return null;
     this.pos += len;
-    return Buffer.from(this.buf, this.pos - len, len);
+    return Buffer.from(this.buf.subarray(this.pos - len, this.pos));
   }
 
   readBufferRemaining() {