Hmm, rotating... just works.

with all files loaded i got 1-3 fps. But i'm only doing this to see whole thing from time to time. Normally i'm working on small groups, then merging them into main groups - currently five of ten are more or less made.
Usually there is no problems with making details in FC, only two annoying things are: sometimes i could not make desired fillet/chamfer because model already is too complicated for them works, and slow to very slow sketcher when using more tangents or especially symetric constrains. Or just a lot of them...