QUOTE(LamontStormstar @ Mon 13th October 2008, 10:44am)
Hmm... isn't the native PHP interpreter written in C++ or something low-level?
Yes, and in addition there has been a lot of work done to integrate PHP with Apache, the dominant web server out there. This ameliorates a good deal of the overhead of the interpretive nature of PHP, but not entirely. It is likely that what has been said above is true, which is native C/C++ CGI modules are faster than Java, which is in turn faster than PHP, which is in turn faster than Python, which is in turn faster than Ruby. But this, of course, obscures vast amounts of other complexity that depends on what it is you're trying to do. A large stream of poorly-designed SQL queries will use up vastly more time than any amount of user interface cruft you can imagine.
Recall here that Yahoo runs on a LAMPs engine (Linux, Apache, MySQL, PHP), and it seems to perform well under high levels of load.
The two useful ways of improving Wikipedia performance would be to optimize the database queries and structure, which (given the size of the existing dataset) is probably impossible, or to re-implement the core Wiki functions in C++. In fact, I'm doubtful that even the latter would help, as I suspect the site is database-bound.
On the larger topic, has anyone tried PHP/Cake and have a report to give?