The top-of-my-head story is that PHP5 was quite slow, Facebook's HHVM was PHP-compatible and fast. PHP7 was competitively fast with Hack. In terms of "performa

The top-of-my-head story is that PHP5 was quite slow, Facebook's HHVM was PHP-compatible and fast. PHP7 was competitively fast with Hack. In terms of "performance needed for many users", Facebook doesn't use PHP (a "scripted language") for everything. etc.