I found I was losing time waiting for some of the sets to load (periodically 1 or 2 images in a HIT take a really long time and ultimately fail to load)... So I have 2 HITs accepted at once, running in separate windows side by side, and I just alternate between the two so that in case one is slow to load, I just rip through the other one..
I also have a Page Down mapped to one of the extra buttons on my mouse, and I have a Enter mapped to another one of the extra buttons, which helps me move a little faster too since I don't need to use my keyboard or left hand at all.