Slow PHP script - automatic debug and diagnosis?

Enable XDebug profiling, and send the resulting files through WinCacheGrind (Windows) or KCacheGrind (Linux).

This will allow you to see a breakdown of which functions get called most, and where the time is spent. Learning to use XDebug is a must for any serious PHP developer.

Here is a seemingly good tutorial on getting started with XDebug profiling.

You will need two tools

• a profiler (Google it)

i use this one at work :

http://www.nusphere.com/products/php_profiler.htm (commercial)

• a load tester

check this site for more info :

http://performance-testing.org/content/performance-testing-tools

I'd recommend to use a PHP profiler. Xdebug which is both PHP debugger and profiler can help a lot. There are also other debuggers, e.g. Zend Debugger.

To analyze profiling results you could also need a special tool. I used WinCacheGrind in Windows and KCachegrind in Linux.

Profiling report shows tons of useful information e.g. which lines of the source code were called how many times and which functions took the most of the execution time.