Downloads while playing

Why does the game download stuff while we are playing the game?Shouldnt every thing be downloaded when we patch?and i know it should. So many times it happens, a game starts, the game downloads stuff on its own , and my game lags. Its like livepatching even when its not supposed to. Why so fail server management?:
I get a minimal of download while i am in a game, like 15-25kbps download. and its because of the game client nothing else, i checked it. When i Altf4 the game it stops when i reconnect it starts again. Some help with that? also i donno if this is the right forums...the previous forums wont let me post bugs