Die-cut/Contour cut 3 mil laminated stickers, I do them at 400 mm/s. Slower never seemed to be better. Maybe for really large pieces or heavy sheets where you wanted stability and were worried about slip.
I think a lot of cutting issues that folks might think are speed related could be overall stability issues and deforming of things as cuts are made and "weaken" the stiffness of the sheet. Even a tiny 4-5 inch outfeed ledge helps in my case, also not cutting so deep that things pop out on their own is key.