speed comparison of util.format vs array.join vs string concatenation in node version 0.12.2

gistfile1.txt

var util = require('util');
var winston = require('winston');

for (var runs = 0; runs < 100; runs++) {
	winston.profile('utilformat');
	var output = "";
	for (var i = 0; i < 10000; i++) {
		output = util.format('%s: %d: %d: %d: %s: %s', 'testing', i, i, i, 'another', 'once more');	
	}
	winston.profile('utilformat');


	winston.profile('join');
	for (var i = 0; i < 10000; i++) {
		output = ['testing', i, i, i, 'another', 'once more'].join(': ');	
	}
	winston.profile('join');	

	winston.profile('stringcat');
	for (var i = 0; i < 10000; i++) {
		output = 'testing: ' + i +': ' + i + ': ' + i + ': another' + ': once more';	
	}
	winston.profile('stringcat');	

};