Quickly compare the speed of multiple functions

speedtest.php

<?php
/**
 * Example output:
 * function:   file_exists(__FILE__);
 * time:       1.39806 seconds
 * speed:      39.248 %
 * 
 * function:   is_file(__FILE__);
 * time:       0.3417 seconds
 * speed:      85.152 %
 * 
 * function:   is_dir(__FILE__) || is_file(__FILE__);
 * time:       0.56151 seconds
 * speed:      75.6 %
 */

$total = 0;
$content = '';
$executions = 1000000;

test(function(){ file_exists(__FILE__); });
test(function(){ is_file(__FILE__); });
test(function(){ is_dir(__FILE__) || is_file(__FILE__); });

$content = preg_replace_callback('~\{speed:([\d.]+)\}~', function($m) {
	global $total;
	return round(100 - $m[1] / $total * 100, 3).' %';
}, $content);
echo $content;

function test($func) {
	global $total, $content, $executions;
	
	$f = new ReflectionFunction($func);
	$body = trim(
		implode('',
			preg_replace('~^.*?function\s*\([^\)]*\)\s*\{\s*(.*)\s*\}\s*\)?\s*\;?~is', '$1',
				array_slice(file($f->getFileName()), $f->getStartLine() - 1, $f->getEndLine() - $f->getStartLine() + 1)
			)
		)
	);
	$start = microtime(1);
	for ($i = 0; $i <= $executions; $i++) $func();
	$time = microtime(1) - $start;
	$total += $time;
	
	$content .= 'function:   '.$body.PHP_EOL;
	$content .= 'time:       '.round($time, 5).' seconds'.PHP_EOL;
	$content .= 'speed:      {speed:'.$time.'}'.PHP_EOL.PHP_EOL;
}