I’m not sure how current or updated this is because I found some broken project links (all links below work) but these projects seem promising and worth closer inspection, especially if one is looking to make their PHP scripts run faster.
… a free open source PHP accelerator, optimizer, encoder and dynamic content cache for PHP. It increases performance of PHP scripts by caching them in compiled state, so that the overhead of compiling is almost completely eliminated. Also it uses some optimizations to speed up execution of PHP scripts. Turck MMCache typically reduces server load and increases the speed of your PHP code by 1-10 times.
Jason Sheets created http://phpcoder.sourceforge.net/ - PHPCoder - which is a GUI front end to the Turck MMCache Encoder which allows encoding of PHP files and the following options: Expire scripts aftter a certain amount of time, restrict server IP, restrict server name and restrict visitor IP. PHP Coder is distributed under the BSD License.