It also stated that they had a FScreenPPC ready but they wanted to test it more.
Reading the FScreen.doc suggests the application has PPC support already.
I doubt it has anything to do with speeding things up, though, but rather making it work at all with M68K/PPC mixed environment.
In the M68K/PPC context switching environment it is doubtful using PPC for rendering would make it any faster, probably only slower.