So you want to help out, eh? Here's what you can do:
This project is coded mainly in C and supports Linux (>= 3.4). Use only things that are documented, and when possible, try not to use functionality that is exceptionally Linux specific. Ask if you have questions.
Speed is of paramount importance. At the same time, stability is more important - random crashing servers are a problem.
Finally, if you decide to begin contributing, introduce yourself in an issue and tell what it is you want to work on. Or just send a pull request. Either works.