I saw Beakys (Andrews) Tumbler in action the other day. It spins about three quarters of the speed as a clothes dryer. Hope it helps. 
the motor in my tumbler spins very fast, the media rotates at a good speed (cant tell u what the rpm is).
What I think brett was commenting on the speed the parts moved through the media.
I am not sure if mine is a rotary tumbler, mine uses vibration to tumble the media which also tumbles the parts.
