Leveled 72-80 in an hour with 300% elixir as a protection paladin
This is how I did it:
1. Go grind in Nexus from 70 until you are 72-73, do no do the quests yet if you have elixir.
2. Have quests complete ready in Utgarde Keep aswell.
3. When 72-73, fly over to Drak'tharon Keep and LFG Nexus when outside, do Nexus and pop the elixir right before turning in the quests in there.
4. LFG specifik Utgarde Keep while grinding mobs inside Drak'tharon Keep, go inside Utgarde Keep when you get in, turn in quests and leave again.
5. Start farming Drak'tharon keep, do the quests and keep on farming, average level was about 8-10 minutes, no big problems for me as protection pala with full looms and other decent gear.
6. Do the quests and go all bosses but the last, it's worth doing the boring and slow second boss because there are lots of mobs after it.
7. When 79, fly down to Utgarde Pinnacle and start grinding the mobs in there until the elixir have ran out.
I know there is probably better ways to do this but couldn't find a booster and 72-80 in one hour is still pretty good imo, I also still have Elixir of Ancient Knowledge x3. Not saying Nexus it bad but by the time you hit 75+ the xp is going to be way worse.