Hey! thanks for reviewing our game and pointing out a few things. We plan on making a performance and small changes patch here soon within the next week or so. A few of the things you mentioned were just small oversights being this is our first game launch. Also as for the performance issues we never ran into problems ourselves when testing so we will look into that further immediately.
I'm 90% sure performance is not good because of lumen. When I tried lumen myself in ue5 it was as bad, I know I don't have newest PC but I don't know if lumen is really worth it especially for cell shaded game because it's almost not noticable with it , I would suggest to try baked lightning instead (yes it's still possible to use it in ue5) It will look quite similar with a lot better performance.