There is a phased event in Deepholm where you are attacking the twilight hammer guys for the Therazine rock jabba girl. I sat there for 30 min just plowing non stop mobs at 4k xp a kill and had 5 npc's helping with spawns of up to 6 guys to kill.

I could have easily stopped there and just 1 button heroed my way from 82 to 85 there in half a day im guessing.