I was making string blocks today (6600 in set-in table) and got impatient, kicked up the speed button and the machine nearly came out of the cabinet it was bouncing so bad.
I think the high speed usage is only really good when a machine of any kind is clamped into a table. I've heard the original poster's complaint many times over the years about all kinds of machines.
I do hope there isn't any thing wrong with your machine!