Performance check about object initialization.

bench.js

var before, after;
var obj, i;
var count = 1000000000;
var t;

console.log('%j', process.versions);

console.log('');
console.log('* initialize');

before = new Date;
for (i = 0; i < count; i++)
  obj = {};
after = new Date;

console.log('{}:\n  %d ms', after - before);


before = new Date;
for (i = 0; i < count; i++) {
  obj = {}; obj.__proto__ = null;
}
after = new Date;

console.log('obj = {};obj.__proto__ = null:\n  %d ms', after - before);

console.log('');
console.log('* lookup');

obj = {key: true};
before = new Date;
for (i = 0; i < count; i++)
  obj.key = true
after = new Date;

console.log('obj = {key: true}:\n  %d ms', after - before);


obj = {key: true};
obj.__proto__ = null;
before = new Date;
for (i = 0; i < count; i++)
  obj.key = true
after = new Date;

console.log('obj = {};obj.__proto__ = null:\n  %d ms', after - before);

OS: Mac OS X 10.7.5

{"http_parser":"1.0","node":"0.8.15","v8":"3.11.10.25","ares":"1.7.5-DEV","uv":"0.8","zlib":"1.2.3","openssl":"1.0.0f"}

* initialize
{}:
  5723 ms
obj = {};obj.__proto__ = null:
  5628 ms

* lookup
obj = {key: true}:
  1666 ms
obj = {};obj.__proto__ = null:
  1084 ms

{"http_parser":"1.0","node":"0.8.15","v8":"3.11.10.25","ares":"1.7.5-DEV","uv":"0.8","zlib":"1.2.3","openssl":"1.0.0f"}

• initialize
  {}:
  5391 ms
  obj = {};obj.proto = null:
  135251 ms
• lookup
  obj = {key: true}:
  1445 ms
  obj = {};obj.proto = null:
  1308 ms