Probably just too many assets that it almost causes the game engine to almost crash when it has to load that section. Probably work on simplifying it a little bit. Without sacrificing too much on the look. Unity engine can only handle so much.
Just in this scene there are not so many assets, I think I messed up with the vfx smoke. And the monitor shows the drop in fps is in scenes where there is smoke, it seems it gives the biggest load.
