Well, it's kind of hard to know what the problem is without more info, but if he has lag with the regular volume control then that's really strange, that is a hardware feature and should be changing instantaneously, if he means that there is a lag when changing the eq settings then that's more of an architectural limitation of rockbox the playback engine is not designed for low latency, it has a low latency mode though which is used for example when changing sound settings but there is still a delay that is easily heard.