Facebook actually does some compile-time optimizations, but also ships some of the profiling data for JITing between early deploy phases and the rest of the fle

Facebook actually does some compile-time optimizations, but also ships some of the profiling data for JITing between early deploy phases and the rest of the fleet: https://engineering.fb.com/2021/03/03/developer-tools/hhvm-jump-start/ https://engineering.fb.com/2021/03/03/developer-tools/hhvm-j... Also, Facebook used to do ahead of time compilation (HPHPc) but eventually HHVM managed to outperform it.