On my install (63 folders in GameData, AVC reports 29 mods and I've removed many similar parts), I usually sit at 1.78G on the startup screen, with ~1.8G in the VAB in an otherwise empty sandbox save with a modified cfg with scale & normals_scale set to 8. With the aggressive 4.0 beta installed with scale back up to the default of 2, I'm now sitting at 628MB(!) on startup screen and 950MB(!) in the VAB. Generation of the cache took well over an hour, and it was well worth it. I'll report back later today after having played a while if I notice any issues.