Depending on the nature of your code, just throwing pypy at it instead of cpython can be a huge win. This very much depends on what you're doing though. For example, I have a graphics editor I wrote that is unbearably slow with cpython; with pypy and no other changes it's usable.

If what you're trying to do involves tasks that can be done in parallel, the multithreading (if I/O bound) or multiprocessing (if compute bound) libraries can be very useful.

If what you're doing isn't conducive to either, you probably need to rewrite at least the critical parts in something else.