Using Zend Optimizer
Zend Optimizer™ is a free application that runs the files encoded by the Zend Guard, while enhancing the performance of PHP applications.
Zend Optimizer is installed on all Linux Shared Hosting accounts for PHP4. Customers can upload newer versions of Zend Optimizer (and other PHP modules) and reference the path to their files.
CAUTION: This will not work with PHP5. If you attempt to use the installed version of Zend Optimizer with PHP5, it will cause problems.
If you want to use your own php.ini and Zend Optimizer, add the following to your php.ini:
[Zend]
zend_optimizer.optimization_level=15
zend_extension_manager.optimizer=/usr/local/Zend/lib/Optimizer-3.3.3
zend_extension_manager.optimizer_ts=/usr/local/Zend/lib/Optimizer_TS-3.3.3
zend_extension=/usr/local/Zend/lib/Optimizer-3.3.3/ZendExtensionManager.so
zend_extension_ts=/usr/local/Zend/lib/Optimizer_TS-3.3.3/ZendExtensionManager_TS.so