Zend Optimizer

Zend Optimizer is a comprehensive software package that helps to improve the performance of PHP projects, allowing for an increased speed of code execution.
This is made possible by the integrated Zend run-time compiler that acts over the intermediate code, ensuring that results are carried out faster.
Being designed as an extension for the PHP engine, the program performs an automatic optimization of the scripts, while detecting files encoded by Zend Guard (an obfuscation tool developed by the same company as Zend Optimizer).
As far as prerequisites are concerned, you need to have PHP 4 or 5 deployed on the system, as well as a web server such as IIS or Apache (1.x or 2.x). During the installation process, you will be asked to provide the location of the PHP.ini file, which contains essential information necessary for a successful deployment and runtime.
In order to verify that Zend Optimizer has been properly installed, you can make use of a simple PHP function, namely phpinfo(), which should return basic information (such as version and copyright) about the program if everything worked out.
Note that there are some tweaks that are necessary for Zend Optimizer to run as expected: PHP features such as Debug Mode, Thread Safety and Enable Versioning should be disabled and various third-party PHP extensions should be deactivated or removed, as they may cause incompatibility issues.
The optimizer can be customized using the directives located in the zend.ini file, using the Zend Platform or the Zend core.
As a conclusion, Zend Optimizer is a reliable PHP extension that can speed up code execution. It is aimed at advanced users that have the necessary know-how to make the complex configurations needed to run properly.