When i fist make a save and add some solids with deco (not much <2500 parts), the fps is very low (17fps) on a capable computer. When i save and reopen it, the fps goes back to normal (50ish fps).
A capable computer is a core i5 running at 2.6ghz, with 6gb of ram, and a 300gb hard drive, a NVIDA Geforce G105M, and windows 10.
have you leaved TPT opened for long? any save opened for too long can cause lags, example:id:2106073