Thanks for your replies, the "within seconds" maybe overstating it, but it should be done within the time it takes for the load to pick up. Let's say without scaling it takes 4 hours, using the higher CPU it takes 15 minutes. If now it takes 5 minutes or 10 minutes for nodes to join and then be fully available it still takes it down from 4 hours to 1hour. But the faster and more dynamic the better of course.