@d4mich4-At the beginning, the little box that pops up in the opening menu, it clearly states that the option to turn of the music/SFX can be found by right-clicking.
I agree with HammerNsickle. Though, my computer ususally isn't very slow, nor is it terribly old. This games seems fun, I usually like these types of games, but it's just way too laggy to be worth it.