jack, they are not slow at all. Actually, I had to set it slower than you would for a mouse (which I have too but don't use). The movement with the thumbkin is very little and gentle. I love the thing. Never again a mouse. And I am at least 8 hours a day on the PC.
This is a free country. There is room for any option. I put a big towel (folded 4 times) under my keyboard, rest my arms on my horizontal armrests, rest my hands on the towel and just swivel the thumbkin a little. No stress at all and VERY fast.