Sorry, me again. Just reporting something Ive noticed. I doubt this would be noticed by many users, as the effect only becomes pronounced when working at print(large) resolutions, and only then if you're pretty in tune to the nuances of your software's performance. Keep in mind, Ive just moved to this new Vista system configuration, so any differences are jumping out at me a bit more. It seems like it might be a vid card/program interaction issue, and the Nvidia 64 bit drivers are notoriously problematic, though I have no way of knowing for sure.

Situation: Any time I create multiple layers in a document, and adjust the opacity of one layer (adjusting transparency % by dragging the slider, toggling visibility on/off) then continue to sketch/erase on another layer, my performance is noticeably impacted.

Stroke quality diminishes, taking on curves that look more like series of short segmented straight lines, rather than smooth responsive curves. "Lag" wouldnt quite be the correct term, so much as the brush seems to "hang" seems "sticky". Also, faster strokes are sometimes marked by long coarse black visual artifacts..."tears" in the image.

Solution: If I turn off 3D lighting (f5), then turn it back on, the situation seems to "reset" itself, and performance returns to normal.

Obviously, working with larger images places a greater perfomance burden on your system. I'm pretty sure I can detect the beginnings of the same perfomance hit when trying to do the same thing at default size documents, although its not nearly as pronounced, and I dont get the artifacts....its only when I move to print quality image sizes it becomes pronounced enough to really notice. But these documents are within the tolerances for the images I was working with on my previous system configuration, and they do perfom well enough, even across multiple layers, as long as no opacity adjustments are made.

AR2.519, Nvidia forceware 129.25, Vista 64 Ultimate

AMD Opteron 180(dual core) , Geforce 6800 GT, 3 gb ram ( I lost the ability to mount 4 gb of ram when I installed the dual core processor, due to a quirk with my motherboard, but Ive still got more ram availaible just by virtue of moving to Vista and 64 bit from XP 32, so this really should not be a factor). Will provide advanced system info on request.