I never really have any slowdowns, and I'm on a radeon 9600 pro mobile. The only thing I do notice is that with paint fx and while working with surface points or isoparms there is a red trail left behind where the pointer was until you stop dragging. That's a real pain, but you can work around it for the most part. Also, it seems the lasso tool has a similar problem.
"We don't actually need to know that the main character has a past. All we need to know is that he has an objective and a lot of people are going to die and a lot of innocent inanimate objects are going to be destroyed and blown up before he can complete that objective."