Hi!
The last time I saw someone asking if it was faster on #hhvm the answer was "not yet". Whether strong typing is a pro or a con of Hack vs PHP seems like a religious debate that I'll try to stay out of until the issue is forced. The bits most likely to be of interest in the short term are the `async` and `await` keywords [0] and possibly the Continuation class [1] which makes creating generators easier than the PHP Iterator interface.
PHP 5.5+ has actual generators: http://php.net/manual/en/language.generators.overview.php
The typed code would not be faster by itself unless some optimizations actually using type information would be done (not sure if HHVM has such optimizer), but that would require writing actually typed code which would not be PHP of course. And this probably will be useful only for scalar types, since there's not much happening at runtime with non-scalar typing that can be eliminated by stronger types (for scalar types, conversions and type branches in operators, parameter passing, etc. can be eliminated).