3v4l.org

run code in 300+ PHP versions simultaneously
<?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;

preferences:
29.93 ms | 402 KiB | 5 Q