Did you know that the fastest way to check in PHP to see if you’re running on windows is:

$iswindows = DIRECTORY_SEPARATOR == '\\\\';

or the fastest way to get the time without even calling a function is:

$currenttime= $_SERVER['REQUEST_TIME'] ;

These are some of the optimization methods mentioned over the slides by Ilia Alshanetsky on High Performance PHP. Browse the slides to learn more optimizations you can perform on your code to improve performance:

http://ilia.ws/files/ez_performance.pdf