PHP Accelerators/Cachers will boost the performance of your PHP applications, by caching the compiled form of php scripts to avoid the overhead of parsing and compiling the code every time the page is loaded. A PHP accelerator typically reduces server load and increases the speed of your PHP code by 1-10 times. Normally you will install these in the form of a php extension.
This list contains all the php accelerator solutions available at this time, with a short description