- microtime: documentation ( source)
<?php
$tstart1 = microtime(true);
for($x=1; $x<=5000000; $x++);
$tstop1 = microtime(true);
print $tstop1 - $tstart1;
print" > ";
$tstart = microtime(true);
for($x=1; $x<=5000000; ++$x);
$tstop = microtime(true);
print $tstop - $tstart;