So Blizzard posted on its official forums today that the lag we have all been experiencing in Northrend is directly tied to Wintergrasp. What bothered me is the fact that nothing was mentioned about the lag IN Wintergrasp. It becomes a lagfest in Wintergrasp to the point to where you can cast a spell, eat lunch, read The DaVinci Code, then come back and play!

Also, lag experienced in Naxxramas will be fixed in a minor patch in the future. Whether or not that patch is the 3.0.8 patch wasn't mentioned.

Link here.