Zone stability? Yes, there's that too, Dotsu, at least until the zerg-style rushing will become less common. Frankly, I'm impressed than the area (and the client) can hold up during some of those horde moments...

Ahem... I digress. I think five minutes is indeed a lot of time, but three might be a fair compromise unless the devs resort to other measures such as instancing, preliminary requisites (clearing lesser mobs, needing an elite permit, or even tweaks to the enemy AI). So, I think Eric's take on Militaratus's idea is reasonable.