<?php

$original = 'prepend/youtube#video/postpend';
$counter = 1000;

$start = microtime(true);

for ($walk = 0; $walk < $counter; $walk++) {
    $computed = preg_replace('/youtube#video/', '', $original);
}

$end = microtime(true);

echo sprintf('preg_replace took %f', $end - $start) . PHP_EOL;

$start = microtime(true);

for ($walk = 0; $walk < $counter; $walk++) {
    $computed = str_replace('/youtube#video/', '', $original);
}

$end = microtime(true);

echo sprintf('str_replace took %f', $end - $start) . PHP_EOL;