WinCacheGrind is a graphical tool used to analyze the cachegrind.out files generated by Xdebug. This is an open-source project and you can download the latest release from its website at http://sourceforge.net/projects/wincach egrind.

Installation should be simple—just download the installer package and follow the step-by-step instructions. The tool should configure itself and work out of the box with the default options. After installing it, run the graphical tool itself.

From the main menu of WinCacheGrind, choose File, then Open. Browse through to c: mpxdebug and open one of the cachegrind.out files. Your WinCacheGrind screen should look like the following:

One of the most useful features is the ability to analyze the script execution as a whole, and see which function is using the largest portion of the time, and then drill down on that particular function and analyze its information. For relatively complex websites or applications, this can be crucial to tune the performance of some parts of your code that you don’t expect are performance bottlenecks.