Optimization // Encoding
Do you have Zend Optimizer or IonCube installed? These will show on the PHPInfo script mentioned in my aforementioned post in the area mentioning:
This program makes use of the Zend Scripting Language Engine
it will specifically mention IonCube or "Zend Optimizer" if installed (there are several Zend extensions pre-installed, we're specifically looking for Zend Optimizer here).