stream: use fast-path for only large inputs

Author: anonrig

lib/internal/streams/utils.js

@@ -278,7 +278,7 @@ function isErrored(stream) {
 function encodeWithFastPath(input, encoding) {
   const enc = normalizeEncoding(encoding);
 
-  if (enc === 'utf8') {
+  if (enc === 'utf8' && TypedArrayPrototypeGetByteLength(input) > 512) {
     const buf = encoder.encode(input);
     return new FastBuffer(
       TypedArrayPrototypeGetBuffer(buf),