I'm all for putting new whiz-bang features on the back burner for a year, if at the end of the year, AE emerges as a product that will have many Smoke and Flame users concerned for their investments :) 

RAM previewing for simple playback is soooo 1999, and the current multiprocessing functionality rarely, if ever, works reliably. And there are some features like Rotobrush that I would use a LOT more if they weren't so painfully slow (it's a bummer to see RB using only one of my CPU cores, and I find that Rotobrush slows down my comps, even when I've frozen all my RB segments). And has been mentioned before, a scanline rendering mode would make things like Region of Interest significantly more useful (and would make those of us spoiled with similar functionality in Nuke very happy)

After Effects is literally at this point, "the kitchen sink", in regards to "creative features". I am hard-pressed to find any major "creative features" on my wishlist that I would welcome before a general performance overhaul.