welcome to the forums
yes, you haveless traction on ice (about 40% of normal traction, possibly less) so naturally the speed must be cut. If you've ever driven on ice in real life you realize this. Being a Winnipegger, i spend about 6 months a year on ice

--well maybe more like 4.5
anyways...
please use the search button to find other threads about the DFP
there are about 5 threads sitting on this forum already discussing how individuals drift with the DFP on 900 degree mode, we dont need another redundant thread discussing what has already been covered in this area.
also - have a look at the 900 degree demonstration videos submited by Mike le Chat Noir, BreakerOhio, Ryen49, foshoazn (i think), and others
sorry to those i may have forgotten.
with regards to your wheel speed problem: just practice more adn dont worry about breaking the wheel (just dont fling it off the table, or whatever you have it mounted to

). If the force feedback is limiting your speed, turn it down.
Drifting.. Steering Options
you might also find it helpful to look through some of the threads located in this
Link