Ruby and Python could help -- but depends what you're doing. They aren't going to magically make your DB queries faster... but certain libraries can perform many, many times faster.
Though, that's the library, not the language.
Though, that's the library, not the language.
But you should be hiring to solve a problem -- seemingly speed and reliability, in your case -- not for a language.
But yeah, tell them what stack they will be working on ;)