Grim Dawn (80 FPS [Performance] or 60 FPS [Balanced] or 40 FPS [Quality]):
Window Mode -> Fullscreen
Screen Resolution -> 1280x800
Anti-aliasing -> On
Anisotropic Filtering -> x4 (80 FPS [Performance]) or x8 (60 FPS [Balanced]) or x16 (40 FPS [Quality])
Textures -> High
Shadows -> Medium (80 FPS [Performance]) or Very High (60 FPS [Balanced]) or Ultra (40 FPS [Quality])
Deferred Rendering -> On
UI Scale -> Default
Fullscreen Gamma -> Default
Shaders -> High (80 FPS [Performance]) or Very High (60 FPS [Balanced]) or Ultra (40 FPS [Quality])
Reflections -> Medium (80 FPS [Performance]) or High (60 FPS [Balanced]) or Very High (40 FPS [Quality])
Particles -> Medium (80 FPS [Performance]) or High (60 FPS [Balanced]) or Very High (40 FPS [Quality])
Lighting -> Medium (80 FPS [Performance]) or High (60 FPS [Balanced]) or Very High (40 FPS [Quality])
Weather -> Medium (80 FPS [Performance]) or High (60 FPS [Balanced]) or Very High (40 FPS [Quality])
Color Blindness ->
Vertical Sync -> Off
Triple Buffering -> Off
Detail Objects -> On
Alpha To Coverage -> Off
Ambient Occlusion -> Off (80 FPS [Performance]) or On (60 FPS [Balanced] or 40 FPS [Quality])
Post Processing -> On
Depth of Field -> Off
Soft Particles -> Off (80 FPS [Performance]) or On (60 FPS [Balanced] or 40 FPS [Quality])
(!: 45 FPS can also be used instead of 40 FPS on the Steam Deck OLED.)
Last time I played the game have frequent freezes, for a second or so every couple minutes.
Did you try playing it with proton experimental.