I'm ze dualboxing virgin, have done it only for a while, but when it comes to leveling, I think I've found a shortcut. (if this is a repost, then nvm me)

My main is a mage with lots of t6+ and equivalent gear, so I wanted just to boost one toon on my RAF account to 60 for some more farming and fun. My first idea was to level a toon for another account just for mining, so whenever I'll be raiding, I could have RAF account online, parked next to rich ada deposit somewhere..

So I boosted my RAF toon just by dualboxing all the quests, and when he reached 45, I went to Scholomance since I can clear the place quite fast (though skipping magic immune skeletons by jumping down the bridge and opening the door and entering with invisibility, then summoning RAF toon in)

Since my mage is 70 naturally, there were no RAF bonus XP at all, but.. I killed Ras Frostwhisper, and RAF toon got insane XP from that, over 1,5k xp anyway. And this was because Ras is lvl 62 (so my main would had got XP from killing it, if he were not level capped already)

Then I had an idea, I used to farm a lot @ Bash'Ir Landing / Blade's Edge Mountains, I flew there with my main, and now I needed to find good spot for my RAF toon, so he wouldn't aggro because his low lvl. As we all know, there are lots of "spikes" around BEM, so I landed on one (which was far away from the ground), and started summoning my RAF toon.

I made it from 48 to 60 roughly in one day, here are the XP what my RAF toon got:

raf| 70| 71| 72|axp|m2k (axp = Average XP lvls 70 71 72) (m2k = Mobs to Kill / level)
55|744|762|777|761|195
56|759|774|792|775|199
57|774|789|807|790|203
58 |789|804|822|805|206
59|801|819|840|820|210

So for example when my RAF toon was 57, he got 807xp when my main killed lvl 72 arcanist mob down there. On those levels, only around 200 mobs need to be killed for each level.

So the boosting was kinda free, since I would had farmed a lots of those Prison keys and netherweave cloths anyway. Dualboxing now the quests in Outlands ^^

Hope this helps, and wasn't very old information