The IBM developerWorks website has posted the first part of a series looking at boosting the performance and throughput of your PHP applications through an opcode caching software, specifically XCache.
PHP is a scripting language most often used to create Web applications. It's easy to learn and produces visible results quickly. However, because PHP is interpreted, PHP code is parsed and translated to opcodes every time it executes. An opcode cache eliminates that rework, making PHP applications faster.
They start with the installation of the software (just XCache, they assume everything else is installed) and what to edit in the php.ini file to get things up and running. They follow this up with a sample benchmark for a local phpmyadmin installation.