Facebook platform's enormous success has been fueled in part by the LAMP stack. A large PHP code base leveraged over many servers poses unique efficiency challenges, both in terms of machine utilization and electric energy consumption. The open-sourced Hip Hop Virtual Machine is running on all of Facebook's production servers at better efficiency than all of today's PHP engines. This talk describes the state of the art in getting PHP code to run efficiently through a combination of bytecode interpretation and Just-In-Time compilation and optimization.