Subsonic is nice, but I'm running it on a Raspberry Pi 2 and you really can feel how haevy Java is on a machine like that. It would be nice to have a lightweight server with the same API but no webfrontend and written in C or go or something for speed. Right now, when I want to start playing a song it sometimes takes up to a couple of seconds what should be instantanious in for example Clementine.