Compatibility Report

• Name of the game with compatibility issues: SIGNALIS
• Steam AppID of the game: 1262350

System Information

• GPU: RX 6800 XT
• Video driver version: mesa 1:26.2.3-1
• Kernel version: 7.2.6-arch2-1
• Proton version: Proton 9+

I confirm:

• [x] that I haven't found an existing compatibility report for this game.
• [x] that I have checked whether there are updates for my system available.

steam-1262350 proton7.log

steam-1262350 proton11.log

Symptoms

HUGE performance degradation.
It is a well known indie game with pixel graphics and uses low poly 3D elements, it shouldn't get me 70fps on a mid range PC like mine (specs attached on mangohud OSD as well as the proton versions).
Tested in proton 9, 10, 11, proton-ge 11, protoncachyOS 10. I don't think I need to screenshot more, something went wrong between 7 and 9 (proton 8 straight up doesn't work for me). and the GPU usage went down by a lot.
Everything was tested with the same Mesa version, same Steam client and game version with the same graphical settings.

Reproduction

open SIGNALIS with proton 7
check performance
open SIGNALIS with proton 9 onwards
check if performance has been degraded.