Question for your question: Did lag from Wintergrasp ever carry over into other zones?

Can't say I noticed, but I don't have the Wintergrasp Timer add-on.

Plus I'm an Oceanic player so lag is either 300-450 or a redline spike up to 1200. One server meltdown, it hit 3000 or so. In Stratholme. Unable to move or even open bags, while a swarm of angry level 60 skeletons slooooooooooowly beat my 80 to death. Fittingly, Baron's mount dropped when I logged back in the next day.

Dalaran is above Crystalsong, it's a zone within a zone. Like I said in my post below, Crystalsong mobs show combat log actions even when you're in Dalaran, so the mobs are obviously loaded and doing things even when you're in Dalaran and haven't been to Crystalsong in hours.

If you lag in Dalaran, you probably will lag in the piece of forest under Dalaran; WoW servers seem to operate mostly in 2D when it comes to deciding what information to send to the client, which means for places with multiple levels people can stand on, you get the simultaneous performance hit of all the levels. Next time you are collecting Crystalsong Carrots, pay attention to your frame rate; it should fall to a little above Dalaran levels whenever you get exactly under Dalaran.

Yo dawg we heard you like zones, so we put a zone in your zone so you can lag while you lag!

I lagged when I should have ligged.