Well, if you are online and playing with others then information could be coming through that is sound related. But without the sound on, that data is not needed, so it is not requested by your game client and would be lower bandwidth.
But you can now limit this down to specific instances. All games, but only when online and only when sound is enabled.
Glad you got help while I was out for the weekend. We are closer to limiting this down and fixing it...