Talk:HipHop

XHProf
XHProf discussion is orthogonal to HipHop as XHProf is a Zend PHP extension (not a HipHop one). My understanding is that HipHop does implement a XHProf-like interface somewhere in its codebase that may or may not be API compatible with XHProf

Missing discussion of HHVM
We probably should add a discussion on that HipHop on MW is deferred (currently) until HHVM is available in late 2012.

discussion of extensions directory
We probably need a discussion on setting up and adding extensions to the compile path a la Manual:$wgExtensionsDirectory. The reason, at least is that the variable may not be set, and, if so, will be set to the wrong path vs. non-compiled installs ( $IP/../extensions instead of $IP/extensions ). If people want to compile an extension into HipHop they need to know both how to configure it into their LocalSettings and where to place the extension.