Used Quercus (the actual php -> java bridge) years ago. I can't recall exact numbers, but generally was about 50-80% faster than the same php based site using a

Used Quercus (the actual php -> java bridge) years ago. I can't recall exact numbers, but generally was about 50-80% faster than the same php based site using a well tuned xcache install (ie, both avoiding the file load/compile). Ran it using resin, tomcat, glass fish, and jboss. No real difference by app server. That said, the biggest issue is always site design. Page too big, too many queries, too many assets loaded, etc. will not benefit much from Quercus or any similar technology.