PHP in a Nutshell

Use the Zend Optimizer

The Zend Optimizer is a free product that helps your PHP code go faster by changing your compiled code around (but leaving the "meaning" of the code the same) to increase execution speed.

Even though it runs every time your page is executed, it has little to no noticeable overhead and can drastically improve performance. Note that there are some cases where using the Optimizer will actually slow things down—usually when scripts are short or exit early. Even these situations become irrelevant if you install a PHP code cache (see next section).