Anyone actually played Guardians of the Galaxy smoothly?

I'm using Nobara HTPC edition and I have the Epic version of Guardians of the Galaxy running via Heroic Launcher. So far I really can't have it run smoothly. The FPS is literally 1-10 fps so even exiting the game is very hard LOL. Most of the time this is the case even in the main menu, sometimes the main menu runs fine but once I load my save, it slows down again.

I think I've tried everything I could think of. I installed gamescope flatpak which fixed the HDR being washed out albeit I still can't make gamescope work in desktop mode. I've tried running the game in desktop mode both via Heroic Launcher and via Steam. I've tried the same in gaming mode and the game is still very slow. There were rare times I got the game working fine but I can't seem to find a consistent way to get that performance.

I even tried using low preset and 50% resolution scaling and it's still the same. I'm looking at VRAM usage and it seems to always maxed out to 8GB which is my GPU's VRAM. Could it be the reason?

This doesn't happen on Windows even if I max out the settings. The thing is I already finished this game on Windows and I just want to play New Game plus as a test game on Linux but it won't let me 😅