I'm running a WAMP (2003, 2.2, 5.1, 5.3) stack and am seeing high CPU load when running a third party, open-sourced application.
Are there any tools to increase CPU use efficiency for PHP or profile what code causes the CPU load to spike?
Can you switch to Linux?
This may sound like I'm an advocate for Linux but it really is true that Apache and PHP work much better on Linux. It's an established fact that Linux handles higher network workloads than windows.
It may not help you much but if you're serious about your hosting your app and you can do this then I would look into it. Then look at the HipHop compiler. A JIT compiler for PHP developed by the facebook guys. https://github.com/facebook/hiphop-php/tree/vm