What do you mean exactly with responsive and snappy? Not loading fast enough? There is definitely a problem when using this game on a mobile device with a 3G connection, but on a normal dsl/cable connection, at least for me, it runs very smoothly.

I chose maps because it has a good api and it is something everyone can interact with. You don't have to learn a new technique, just click, drag and pinch or scroll. It is an unlimited source of interactive backgrounds for the game.