also on arch w/ Hyprland on an nvidia card, using proton-9.0 from the default steam compatibility list
most of the bugs are just because of the game being buggy and incomplete, however I did not encounter the same fps issues you have. One issue I did encounter, is hyprland crashing due to lack of vram (i have an 8gb 2060 super), but after restarting I never encountered the issue again.. not sure what happened there lol
For softlocks, on controllers you can hold (menu + A) / (options + X) or (menu + B) / (options + O) or something like that, I only recently found that out tho (i haven't played the game on keyboard yet)
game is amazing tho, wish to see a full release (hopefully with less bugs tho)!