That's a good question. PHP 5.5 with the newly-open sourced (and integrated) opcache gave it a good run for its money before this optimisation sprint [1]. Under real-world 'bloated framework' usage, HHVM was already pretty cool [2]. I'd like to see the results after this speedup.

1. For simple code only - once it's more computationally intensive, HHVM wins. http://www.alexfu.it/2013/10/22/symfony-benchmark-on-hhvm.ht...

2. http://blog.liip.ch/archive/2013/10/29/hhvm-and-symfony2.htm...

The Wikipedia article (https://en.wikipedia.org/wiki/HipHop_for_PHP) says "up to 6x", however, about 2x speedup versus plain PHP was a more typical experience for me when I used it before.