Running 4.1 on Mac os 10.7 on Mac Pro. every time I make an edit (eg using brush tool) the machine starts to update the image as I am brushing. The image blinks on and off, resizes, shifts and then goes to where it should be. I have to pause after every stroke to wait for this to stop before making the next stroke!
This is really unacceptable. My machine has 8 cores and 24 GB ram so that is not the problem.