i don't have maya cloth so i'm going to tell you what i think the problem is.

maya cloth is a simulation, so it reacts to realistic physics, it deforms on it's own and moves according to it's constrains.
applying a deformer on the cloth will/should not work. because the deformer would hinder the simulation and it's dynamics.

another thing instead, of using your subd body as a collision object for the cloth, u can use a low low poly version of the subD body and make it the collision object and parent it to the subd body and of course make the low poly body not renderable. this would increase speed dramatically.
hope this helped.