Simple benchmark example, between the date() function and new DateTime::format() :
<?php
require 'Benchmark.php';
$bench = new Benchmark;
$bench->addTarget('function', 'date', array('Y-m-d'));
$bench->addTarget('object', function() {
$date = new DateTime;
$date->format('Y-m-d');
}
);
$result = $bench->execute();
/*
* var_dump($result) :
*
* array (size=2)
* 'function' => string '100%' (length=4)
* 'object' => string '122%' (length=4)
*/