Deck BIOS:

• Increase UMA frame buffer to 4G

QAM:

• Disable frame limit
• Set refresh rate to 60hz
• Allow tearing
• Enable half rate shading

In-game settings:

• 1280x800
• Fullscreen
• Disable motion blur
• Disable ambient occulsion
• Enable sun shafts
• Enable bloom
• Disable anti aliasing
• Graphics quality on low
• Texture quality on high
• Disable V-sync
• FPS limit at 60

Tried lots of configurations, including those aiming for 40fps with higher settings, but nothing is very stable.

The game looks very similar at Low quality and High. Textures are increased because otherwise LODs are very visible.

Half rate shading does make the game look a bit worse, but it's stylised so you get used to it, and it's worth it for higher frames.

There are some areas, such as Slacktide, which drop frames seemingly randomly - sometimes it drops below 40, other times stays comfortably above 50. It also reacts to V-sync and frame caps very inconsistently - not sure if it can be fixed but the resulting experience is still good enough, and definitely better than Switch.