How to fix frame rate for 3D part of a 2D game

Hey there! I’m working on a game that begins in 2D but has a part that switches into first person. I’ve been trying to pull this off seamlessly and I’m able to transition from the 2D part to the first person part, the only issue is that for some reason the frame rate tanks when it goes to first person.

I originally started the project in 2D mode, but I believe I did import most of the basic assets. My 2D parts run fine. I also destroy all previous 2D parts when I transition to the 3D part. I achieve the transition by instantiating a new player with the first person rigid body controller script and enabling a new camera. I destroy the 2D player and the 2D camera. But for some reason the frame rate is horrible. I estimate it is somewhere between 10-15 fps. I have another fully 3D first person project with a lot more detailed environments that runs super smoothly so it’s definitely not resource related.

Do you know if there is any harm in having the game set to 2D and then transitioning to 3D? Is there any reason why this would cause the dip? I believe it may have something to do with the map size, as I wonder if Unity thinks that my map is huge? The area that I need to traverse in first person is really small and simple, so I’m really baffled as to why it’s going slowly. If you have any insight into this matter, I’d greatly appreciate it!

This is totally (educated) guessing, but it could have something to do with drawing distance. Your cameras Clipping Plane Far is probably set at 1000 units, try to lower this as much as you can and check if it helps.

If this doesn’t help then please post info from your Stats window while you are in game at that 3D part of the game. You could also post screenshot from Scene view while it is set at Wireframe mode and is close to same vision as the player view.