I really wish there was a way to do inline optimized code, i.e a gen_server that transparently wraps another language without having to get into nif / external servers. Basically an abstraction that hides all of that cruft and builds optimized gen_servers for doing number crunching or heavy processing. Maybe I'm just being lazy. :)

erlexec (or its elixir wrapper) might be worth a try: https://github.com/saleyn/erlexec