The game looks incredible. That's all I was expecting, really. I will skip most of the redundant feedback.
If you are going to shake the screen with every jump, at least don't rotate it around the forward axis. But preferably don't shake it at all.
The performance issues, especially when you hit enemies, stink of some terrible optimization mishap. Are you instantiating prefabs from assets to create each of those particle effects? Do they have unnecessary components in them? Are you using vertex-based cloth physics? This game is running at least an order of magnitude worse than it should. For the immediate future this would benefit a lot more from a visit to the profiler than to a 3D modeling program.