++$i; runs faster in PHP than $i++;
Link > http://my.php.net/manual/en/language.op ... rement.php

There was some article written up not no long ago that I fail to find that was written by a guy who had run massive loops on his server to figure out which was faster.  You'll need a microsecond function somewhere in your application that gets the server microsecond time and echo's it before and after the loop.  I would suggest a loop of 1,000,000 on decent hardware to be able to determine any differences.