PHP/Date/microtime
mixed microtime ( [bool float_output] ) returns a highly accurate reading of the current time
<source lang="html4strict">
<? echo microtime( ); ?>
</source>
Timing with microtime()
<source lang="html4strict">
<?php $start = microtime(true); for ($i = 0; $i < 1000; $i++) {
preg_match("/age=\d+/",$_SERVER["QUERY_STRING"]);
} $end = microtime(true); $elapsed = $end - $start;
</source>