Buffer.concat([])

benchmark.js

var Benchmark = require('benchmark');
var suite = new Benchmark.Suite();

suite
.add("new length 0", function () {
  Buffer.concat([]);
})
// add listeners
.on('cycle', function (event) {
  console.log(String(event.target));
})
.on('complete', function () {
  console.log('Fastest is ' + this.filter('fastest').pluck('name'));
})
.run({ async: false });