From what i can tell, Playmaker is the source for the vast majority of the GC Allocations. I've tracked it down, to the best of my ability, to FsmLog.LogTransition. I have logging turned off but this still seems to show up in the profiler.
A typical frame has about 400-500 calls and is allocating about 80-100kb. I'm not entirely sure if this is a lot. But garbage collecting a megabyte per second seems like a lot.