But that implies that users can already see the benefit, which is not true -- the version of HHVM that incorporates these performance improvements has just been released and it will probably take us a month to upgrade..
Wikipedia runs faster thanks to @hiphopvm. @fbopensource finds Barack Obama's article will load 19% quicker: http://hhvm.com/blog/9293/lockdown-results-and-hhvm-performance