Thanks @puzzlezaddict ! I'll give those a try.
My theory about it being an algorithm that doesn't scale in build mode was wrong btw. I can make the lag inside build mode go away by clicking '...' just like I can make it go away outside of build mode by clicking '...'. That suggests that a state is flipped when transitioning between the two modes causing lag, and hitting '...' unflips it so everything works well again. There is nothing in build mode or live mode that is lagging on its own.
What I can't fathom, is that it's not reproduced yet. SO many players are experiencing trouble with this. And for a good while too, to add.
I think most people aren't reporting it because it's such an OLD problem, most people have given up on it being fixed.
I've had the problem myself for years. On MULTIPLE computers.
Most of the time, hitting ESCape and going back in resolves it temporarily. When it happens, I go into build/buy mode and my framerate drops from 50+ to ~10. I had it go down to 7 (SEVEN) fps just this afternoon. I hit ESCape twice and it rocketed back up to 55. Problem is, it tends to stick in build/buy mode. Once I return to Live mode, I can hit ESC twice and it's back to almost normal temporarily.
