v1.61
DLSS: Off
Dynamic Resolution Scaling: Off
FSR 2.1: Quality
FSR 2.1 Image Sharpening: 0.60
FOV: 90
Film Grain: Off
Chromatic Aberration: Off
Depth of Field: Off
Lens Flare; On
Motion Blur: Off
Contact Shadows: On
Improved Facial Lighting Geometry: On
Anisotropy: 8
Local Shadow Mesh Quality: Medium
Local Shadow Quality: Medium
Cascaded Shadow Range: Low
Cascaded Shadow Resolution: Low
Distant Shadows Resolution: Low
Volumetric Fog Resolution: Medium
Volumetric Cloud Quality: Off
Max Dynamic Decals: Medium
Screen Space Reflections Quality: Medium
Subsurface Scattering Quality: Medium
Ambient Occlusion: Low
Color Precision: Medium
Mirror Quality: Low
LOD: Medium

*using cryobyte33 script + BIOS memory update

From /u/kestononline on Reddit:

I’ll only include the relevant lines. The below settings yield 40-50 FPS.

Video Settings 1:

• VSync: OFF | Max FPS: OFF | Windowed Mode: Fullscreen | Resolution: 1200x800

Graphics Settings 1 | Settings 2 | Settings 3:

• Texture Quality: High (seen from Main Menu settings, not in-progress game)

Resolution Scaling >

• Dynamic Resolution Scaling: OFF
• AMD FSR 2.1: Performance
• AMD FSR 2.1 Image Sharpening: 0.50

Basic >

• Film Grain: OFF
• Chromatic Aberration: OFF
• Depth of Field: ON
• Lens Flare: ON
• Motion Blur: OFF

Advanced >

• Contact Shadows: ON
• Improved Facial Lighting: OFF
• Anisotropy: 1

All in Advanced setting to MEDIUM except the following:

• Distant Shadow Resolution: Low
• Mirror Quality: Low

Steam Launch Options:

• –launcher-skip –intro-skip -skipStartScreen
• (not sure if all of those above do something, but I’ve been using for a while)

Hope this helps some people.

Cheers~ 👍🏽

I get almost consistent 40 FPS using the below settings and setting SteamOS to 40hz and disabling OS based FSR (Setting scaling to auto and filter to linear). 

FSR 2.1 / Auto / Sharpening = 0.50
Texture Quality = High
Crowd density = Low
FOV = 75
Film Grain = Off
Chromatic Aberration, Depth of field, and lens flair = ON
Motion Blur = Low
Contact Shadows and Improved facial lighting geometry = ON
Anisotropy = 8
Local Shadow mesh, Local Shadow Quality, Volumetric Fog resolution, Max dynamic decals, Screen Space reflection, Subsurface scattering, Ambient Occlusion = Medium
Cascaded Shadows, Cascaded Shadow resolution, Distant Shadows, and Mirror quality = Low
Color precision and LOD = High

DLSS: Off
Dynamic Resolution Scaling: Off
FSR 2.1: Quality
FSR 2.1 Image Sharpening: 0.50
FOV: 75
Film Grain: Off
Chromatic Aberration: Off
Depth of Field: On
Lens Flare; On
Motion Blur: Off
Contact Shadows: On
Improved Facial Lighting Geometry: On
Anisotropy: 8
Local Shadow Mesh Quality: Medium
Local Shadow Quality: Medium
Cascaded Shadow Range: Low
Cascaded Shadow Resolution: Low
Distant Shadows Resolution: Low
Volumetric Fog Resolution: Medium
Volumetric Cloud Quality: Off
Max Dynamic Decals: Medium
Screen Space Reflections Quality: Medium
Subsurface Scattering Quality: Medium
Ambient Occlusion: Low
Color Precision: Medium
Mirror Quality: Low
LOD: Medium 

FSR in Performance mode. Texture quality set to Medium.

Tweaked Digital Foundry Optimized Settings (Original By Oliver Mackenzie)

Power draw reported at maximum brightness

Start with Steam Deck preset and make the following changes

Resolution Scaling
AMD FidelityFX Super Resolution 2.1 - Quality

Advanced
Anisotropy - 4
Local Shadow Mesh Quality - Medium
Local Shadow Quality - Medium
Distant Shadow Resolution - Low
Volumetric Fog Resolution - Low
Volumetric Cloud Quality - Medium
Max Dynamic Decals - Medium Ultra
Screen Space Reflections Quality - Medium
Subsurface Scattering Quality - Medium
Ambient Occlusion - High  Low
Color Precision - High Medium
Mirror Quality - Medium High
Level of Detail (LOD) - Medium