It actually uses the MacRuby stuff to compile to native. But the compiler can't optimize nearly as well as it can for statically typed languages, so there's a p

It actually uses the MacRuby stuff to compile to native. But the compiler can't optimize nearly as well as it can for statically typed languages, so there's a pretty significant performance hit on the ruby code itself, though once you've called a native library there won't be any difference.