A GPL’ed (say, it’s not OpenSource, but the source code is available publicly) PHP accelerator has been evaluated at lab, which is called eAccelerator. I should adjust my claim that this sort of application is not useful.
During my test, the accelerator has improved the TPS by about 50%, and is quite impressive.
In order to install this on FreeBSd, you should have installed PHP from ports, and go to www/eaccelerator and ``make install’'.
After the installation, add the following text into /usr/local/etc/php.ini:
Please note that adding extension=“eaccelerator.so” will render a non-usable php installation :-)