HipHop for PHP is a PHP transpiler created by Facebook. By using HPHPc as a source-to-source compiler, PHP code is translated into C++, compiled into a binary and run as an executable, as opposed to the PHP's interpreter based execution. By the statistics HipHop uses improve the performance by anywhere from 3-6 times (depends on the website)
It is free and open-source software distributed under the PHP License and QueryHome is yet to use it???