^^^ This!! Great advice.
Definitely make sure you have no lights in your scenes- that should avoid the need for any sort of shadow calculations. I would check your GPU profiler though to make sure it’s not wasting any time on shadows. If it is, you’ll need to go through and disable shadows on your meshes. I would also probably go ahead and switch Virtual Shadow Maps to Shadow Maps just in case it has to do any setup that it’s still calculating.
I would also make sure any postprocessing effects like Eye Adaptation and Bloom are disabled.
And that’s about everything I can think of. Once you’ve done your optimization pass, check the GPU profiler to see if there’s anything light-related left that you missed.
Overall though, given your game, I think you’ll be fine on performance.