[tikhonj]

No, Haskell really does have significantly better performance than Python or Ruby. Same with some Lisp variants as well--there was even a research whole-program optimizing compiler for Scheme that apparently sometimes beat hand-optimized C (Stalin Scheme).

So one way to improve performance is simply by having a good compiler. And GHC, at least, is a very good compiler.

Also, Haskell support for direct memory control is not that bad. In fact, in some ways, it's better than even Java--you can have your own unboxed data types which essentially act like structs, for example. This also means that you can have unboxed arrays of more than just primitive types.

Haskell also does some very clever things with both the heap and the stack, but I'm not familiar enough with its internals to comment. My understanding is that Haskell makes heap allocation much cheaper and has a GC optimized for handling lots of small allocations (as you would expect for a functional language).

Ultimately, the point is that the question is fairly nuanced and you won't be able to pin down a single language or implementation feature that uniquely determines performance.