2080 SUPER here too and while I also get the seriously low framerate in the menu (1 - 2 FPS for me) I also get 30+ FPS in game on medium settings at 4k (on an empty map) so I’m not too sure what’s going on with your PC unless your CPU is the bottleneck. If I go up to high settings then performance does drop down to ~15 FPS.
I agree the performance is not great and I’m absolutely not justifying it, just throwing in my experience too. It’s mostly playable for me and I can probably live with it until it’s hopefully patched.