REGRESSION Mirror's Edge – Severe Stuttering/FPS Drops
And this doesn't happen with older Proton versions?
And this doesn't happen with older Proton versions?
No, the results are exactly the same. I tested older Proton versions going all the way back to Proton 8.0-5, and the issue still persists.
Unfortunately, MangoHud does not seem to work with these older Proton versions on my setup, so I am unable to provide screenshots with the performance overlay for them, but the behavior and stuttering remain the same.
Could you perhaps post a save that's close to one of those slow down sections?
Could you perhaps post a save that's close to one of those slow down sections?
Yes this is my save
If you're starting from checkpoints B or C in Pirandello Kruger, performance will be poor until you clear the part with the conveyor belts. The issue will not manifest if you begin from checkpoint A.
This is also an issue on Windows, and just confirmed that it occurs on CachyOS as well.
After further testing, I realized this is an engine/game-specific issue rather than a DXVK regression.
I loaded a save file with PhysX disabled in the settings, and the game immediately started in a heavily broken state, stuttering severely at around 30 FPS. However, after letting my character die to force a checkpoint reload, the stuttering instantly disappeared, and the performance shot all the way up to a flawless 535 FPS (as shown in the attached MangoHud screenshot).
Since forcing a level/respawn reload completely clears the performance choke, this seems to be a glitch with how the game engine itself initializes maps or handles internal legacy physics threads on modern systems, not an issue with the translation layer.
@JavaDaVinci Apologies for necroing but thought I'd provide some context. This section of Chapter 6 as well as the Stormdrains section of Chapter 2 has a bug where the PhysX fog emitters still try to spawn even when PhysX is disabled. Ironically, this performance issue goes away when PhysX is enabled (excluding general performance regressions when not CUDA accelerated).
If you're not running PhysX at all, these fixes are harmless:
https://drive.google.com/drive/folders/1atMljlcSYNLQgHQCz45PfpayzXBmNEp4?usp=sharing
https://drive.google.com/drive/folders/1b13KTTtRyunlF-2fpdXMyvjJjt59otCZ?usp=sharing
Proton versions
proton 8.0-5x1 2026-05
Previously, I could play this game smoothly with PhysX turned completely off. Now, it runs terribly all the time.
Even stranger is how the performance behaves when toggling the setting:
When PhysX is turned ON, the game initially runs perfectly smoothly with a high frame rate. However, the exact moment the physics engine is forced to render heavy action sequences (e.g., bullets flying, breaking/shattering glass), the game turns into a stuttering mess and frames drop dramatically.
When PhysX is turned OFF, the performance does not improve—the game continues to run horribly with severe stuttering right from the start, which never used to happen.
Essentially, the game has become completely unplayable regardless of whether the physics engine is toggled on or off.
Operating System: CachyOS Linux
KDE Plasma Version: 6.6.5
KDE Frameworks Version: 6.26.0
Qt Version: 6.11.1
Kernel Version: 7.0.10-1-cachyos (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 5600G with Radeon Graphics
Memory: 24 GiB of RAM (23,4 GiB usable)
Graphics Processor: AMD Radeon RX 6600
Manufacturer: Micro-Star International Co., Ltd.
Product Name: MS-7C51
System Version: 1.0
SCREENSHOT PHYSIX OFF:
SCREENSHOT PHYSIX ON:
LOG FILES:
PhysicXO.tar.gz