Facebook's HHVM (HipHop VM) compiles webpages into native machine code that can be executed directly on the processor. People often confuse HHVM with HPHPc, also made by Facebook. HPHPc came first; it was a converter that converted all the PHP files in a folder into individual C++ files. In other words, you would end up uploading the C++ files to the server, not PHP files. Facebook abandoned HPHPc early on for multiple reasons (it was actually developed by a single developer as a tool for one-time use to convert all of Facebook's existing PHP files into C++, back when Facebook was considering rewriting the website in C++ for improving performance). While the idea for HHVM was loosely based on HPHPc, the approach is much different. HHVM is a standalone replacement for the PHP engine. It has almost 100% support with the native PHP language, up to PHP 5.5, and even (intentionally) reproduces the various bugs in the PHP language, to maintain compatibility. HHVM only replaces PHP, not Apache or anything else in your stack. It is really, really easy to replace it via their FastCGI handler.
I deployed HHVM on a production site as a test, and without changing a single line of code, on average, I saw nearly a 60% decrease in page generation time from the standard PHP binary. Incredible.
HPHPc produced the C++ code and that was compiled into a single binary executable. The deployment process involved using bittorrent to distribute the blob to all of the production servers.
HPHPc wasn't abandoned per say, it was only deprecated once the performance improvements brought on by HHVM were significant enough to justify the transition.
