Sorry no solution here but I thought I'd post to broadly agree with this as well. Whilst I can only speak of my own workflows (CityEngine to Twinmotion) it seems that TM 2023.2 is significantly slower than 2023.1.2 It loads files a lot slower and renders take significantly more time than same scenes in 2023.1.2. Importing of fbx files seems slower in some circumstances. Basic Lumen renders don't crash with me but take a significant amount of time to render to the point where it's not practical to use. For reference I have an i19 (12th gen) 32GBRAM and NVIDIA GeForce RTX 3080 Ti .... I will try a number of different options in TM and if I see any changes report back here....