I don't either, and maybe it's just a matter of perception. Other than the fact that it's a bit jerky, it does what I need. In fact I'm finding that in practice I'm quite satisfied. For the operations that take significant amounts time (import, export, etc), Lightroom on the retina iMac is fast. Outside of Develop I have no problem, and Develop works well enough the way I use it.I have no idea why you found any improvements in the crop tool. I found exactly zero improvement on my end.