Mostly lightings settings cause poor frame rate performance,With Graphics Mod enabled, I get:
~ 30-40fps in the main menu
~ 100 fps in the room menu
~ 10-20fps in character creator
~ 5-10 fps in a scene
on a RTX 5070 for reference. I think this engine is messed up with all the mods going on.
especially during action scenes where stuttering becomes more noticeable.
You can try adjusting individual light settings or simply turning them off.