Mike Willbanks has made a series of posts covering the acceleration tools available for you the PHP developer and some of the benchmarks of using them in an application.

Here's the list:

• PHP Accelerators : APC vs Zend vs XCache with Zend Framework - a comparison of three tools - APC, the Zend Framework components and the XCache tool
• Zend Framework Performance Zend_Loader - a specific look at benchmarks on the Zend_Loader component
• PHP Accelerators: The Missing Details - benchmark results (and code) showing results from testing on the Zend_Loader component
• Accelerators Revisited - a revisit to some of the benchmarks made previously (to change things based on user contributed comments)