First off, there's a lot of talk about this being a recent problem. Was this last week(end) just the time you guys happened to check the numbers and see a spike in DA lag? Or, was that info you could and have looked at before and noticed a spike this weekend? Because if it's #2, it makes no sense to kneejerk change anything when you don't even know why there was a spike.
I'm also completely at a loss as to why devs are so against a specific playstyle of going as fast as possible. It's literally what the majority of everyone in every MMO wants to do. Get xp/levels/gear fast. I get that you want to decrease lag, but it seems like there should be better ways to do it than constantly trying to slow us down (sharn sticky anyone?).
Why not, as someone had mentioned, give enemies smaller range of uhhh noticing you, like in saltmarsh wilderness. That range blows in the wilderness because you want to kill as many mobs as possible, but in a dungeon it would be far more beneficial for people who want to zoom through a quest.
Honestly, dungeon alert isn't going to stop zergers anyway. You can buff up the red name but unless you get ridiculous/vindictive and make them invincible, people are still going to zerg and take the extra 20 sec to kill it, if that. Instead of trying to punish the majority of players for playing one way, figure out a way to change stuff to help us.
For what it's worth, my static group raaaaaaaarely deals with DA. Maybe in 2-3 quests a life I might leave my pet/hireling/whatever out, knowing it'll aggro everything (like in no refunds) because it'll save me maybe a minute of having to chase stuff. They're a little beefier and harry me, but in the end it's slightly easier so that's what I do.