Video done from a Monk perspective. However, the playstyle of constantly moving can be applied to all classes.
One of the most important and most overlooked things about games in general is playstyle. Often people talk about builds and gear, while not talking much about playstyle. In many cases it's not even about where you farm, or what you farm, but rather HOW you farm.
After quite a bit of testing, I'm able to get near 4k kills/hour on MP10 CotA while still killing the elite pack. I'm actually maintaining quite a bit higher kills/hour than players in better gear, simply because of how I'm playing. The other benefit is I can do it, quite well at that, while wearing relatively low eHP gear.
It seems that many players seem to think the game revolves solely around gear, when strategy and play style can make an even bigger impact on farming efficiency. There's obviously some level of gear required, but I was able to do some MP10 CotA at a fairly good kill rate using this playstyle with a fairly low budget gear set (under 100m for gear+gems, no BoA):