How to get cpu consumption of a php script

Hi everybody, I'm a php developper for a high traffic website. Our web servers run with lightty? We have some issues with the cpu consumption of our servers. The problem is that, we don't know exactly which script consumes so much cpu. So, we cant to figure out how much cpu does a php script take. We have tried 3 methods: 1) Microtime: microtime at the beginning and at the end and make the diff. The problem with that is that it takes the execution time of the script, but in our script we make: - connection to database - connection to memcache - connection to session server All of this is not taken into account, so microtime is not that accurate 2) Shell command: we get the pid of the process executing the script and make a 'top' on this pid . The problem is that the php-cgi manages many threads so it's not accurate too. Is there other methods for dealing with this problem. Thanks, best regards, Tanoor.