substr_count vs preg_match_all

substr_count_vs_preg_match_all.php

<?php

$needle = '';
$str = 'hello, world!';
$search_str = 'hello';
$count = 100;
for($i = 0; $i < $count; $i++) {
	$needle .= $str;
}

// substr_count
$start = microtime(TRUE);
$out = substr_count($needle, $search_str);
$end = microtime(TRUE);
echo 'out: '.$out.PHP_EOL;
echo 'substr_count: '.($end-$start).PHP_EOL;

// preg_match_all
$start = microtime(TRUE);
$out = preg_match_all('/'.$search_str.'/', $needle, $matches);
$end = microtime(TRUE);
echo 'out: '.$out.PHP_EOL;
echo 'preg_match_all: '.($end-$start).PHP_EOL;

//out: 100
//substr_count: 7.1525573730469E-6
//out: 100
//preg_match_all: 8.4877014160156E-5