I've tried tweaking various launch options/proton versions and am unable to consistently achieve stable performance. All of my hardware is very modern and perfectly capable of running this game at 120+ FPS as I can get around that level of performance emulating the original PS3 version. Sometimes I'll launch the game and it'll run a bit better, but it's seemingly random. When it's bad, I get around 16-20 FPS on the title screen. Kichijoji is even worse at around 10 FPS. The game resolution/graphics options have no effect on this abysmal performance. My Steam Deck is able to consistently run at 60 FPS with worse hardware, so I'm not sure what's going on here. My gaming desktop's hardware is also very comparable with the Steam Deck's as I have a AMD CPU and AMD GPU (more powerful) running on Arch Linux, almost exactly like the Steam Deck.