Faster PHP: Profile Your Scripts With Xdebug

Xdebug is a powerful PHP extension that can help you track down bottlenecks in your PHP code. From the Xdebug profiling howto:

The profiler in Xdebug 2 outputs profiling information in the form of a cachegrind compatible file. This allows you to use the excellent KCacheGrind tool (Linux, KDE) to analyse your profiling data. Users of the Windows operating system can use WinCacheGrind.

Shown above is a screenshot of KCacheGrind, which is showing that the particular script is devoting a lot of its time to mysql_query calls. Once you know where your code is chewing up cycles, you’ll have a better idea of where to focus any optimization efforts, either by cleaning up ineffecient code and database queries, or by employing a suitable caching strategy.