Going through the same thing and the lag is even worse in live mode. Mind you, I have a pretty mid-high end pc and never experienced a lag this bad until recently and I was starting to wonder if my cpu was bottlenecking (bc I upgraded my gpu not too long ago) or if I didn't completely delete the drivers of the old gpu. I tried almost everything--using ddu, deleting recently installed mods, clearing trays and save files, and yep--turned out it was a Jino hair that I had on 95% of my sims outfits that was causing the lag. If you're having trouble in live mode, only fix for now is to only use it on 1 or 2 outfits. As for CAS, unless the creator lowers the poly count theirself or you wanna go through the trouble of doing so yourself, nothing much we can do about it.