If you are looking for an alternative to Node check out Nimrod. If you just don't like nested callbacks in Node then check out ToffeeScript.

FYI Node is actually compiled so it might perform better than you think. Also it has threads with the module webworker-threads. Node is kind of memory hungry.

Nimrod lets you write clean Pythonish code that is as fast as C and even can interface extremely easily with C libraries if necessary.