Battle.net

Sometimes when I minimize Starcraft 2 into a window the game starts to lag very hard, it takes 3-8 seconds to react to my actions (such as hitting the pause button and having to wait a few seconds for it to actually pause the game) there is also a huge framerate drop. It seems to be random in terms of when it lags on minimizations but it seems that after long games it has a higher tendency to occur. The only way I've figured out to fix it is by quitting the game, either by force quitting if the lag is just too much to handle, or quitting by menu. A characteristic Right when it quits it also seems like it stops lagging 1second before the game window disappears.