BC2 Multiplayer Update 2?

Sorry lads I know this update is ancient but I Just bought the game new (had rented it previously).

Just got an update prompt thats over 400MB and just wondering what the hell it could be?

Had a poke around the web and all I could find was that it rids lag for the most part and has something to do with Onslaught mode, but that info is very much unconfirmed.

Anyone got any solid answers? Any help would be greatly appreciated, thanks a million.

P.S. Whats the story with Onslaught mode anyway? Worth the price or one to avoid?

yeah i kinda regret buying onslaught. i played it once and never gone back to it ever since. i think dice should comlpetely ignore singleplayer for battlefield 3 and just focus on multiplayer. because thats what the battlefield series are known for. BC1 and BC2 singleplayer are so boring -_-