- microtime: documentation ( source)
<?php
$a = 'Something';
$b = 'Other thing';
$startSingle = microtime();
for ($i = 0; $i < 10000; $i++)
$var = 'I am a single quote string '.$a.' & '.$b.' & '.$a.' & '.$b;
$endSingle = microtime();
$timeSingle = $endSingle - $startSingle;
echo 'No math took : ',$timeSingle,'ms';