@phpdeveloper.org
Kore Nordmann has made a post on his blog with more details on the Image_3D package and some of the rendering times he noticed (and the improvements) with the Zend Guard product.
The ZendGuard offers optimization and encoding for your PHP code. I visited a friend who ownes a license of ZendGuard so that we had the idea to test it with something CPU intesinve like Image_3D. The results were quiet surprising.
According to his results, the Zend Guard optimizer actually dropped the effectiveness and speed of rendering an image with his package - up to a 30% drop!