Atelier Ryza 3 receives up to 25% performance boost. On lowest settings at 720p and atelier-sync-fix, the game could perform around 40 FPS before. With SteamOS 3.5.5, it could reach 55-60 FPS.
Under the new update, 800p30 with both TAA and AO enabled can be achieved without upscaling. This is a big deal because the already tiny fonts would no longer be blurry.
https://github.com/ValveSoftware/SteamOS/issues/1176
Workaround is to cap your GPU speed to 1600.