PS. I would like to apologize if I am lacking in many areas or getting something wrong. This is the first time I am using GitHub and the first time ever I ever raise an issue.
Thank you in advance,
-RJ
@UncleRJ Thank you so much for the report! The details about the settings you used were incredibly useful to us, and we were easily able to reproduce the regression based on your description. We are going to look into this and hopefully it is something simple that can get fixed quickly :)
@UncleRJ Hi there! I've taken a little look at the issue.
The 45fps drop you are seeing with Proton 9.0-4 compared to 9.0-3 is actually correct behavior.
Enabling regular vsync should normally limit the frame rate to the refresh rate of the monitor, so 90 for a OLED Deck. Enabling a double vsync will then half that, which in this case would be 45. That it sat at 90 max with the older version was actually a bug.
Besides the above are you seeing any performance difference between Proton 9.0-3 and 9.0-4 when vsync is disabled?
@Blisto91 Hello, thank you for giving this issue your time!
As far as I can remember, disabling Vsync in Proton 9.0-3 won't get me to 90fps, I think it was staying consistent around 60fps with barely any frame drops. I can't prove this point because I can't use Proton 9.0-3 anymore to test it out, so I might be wrong on this one. But I know for sure in Proton 9.0-4 it is worse, more frame drops than in 9.0-3.
It's a little weird that getting 90fps is a bug. I'm currently playing on Proton 8.0-5 to get the 90fps on double Vsync. I guess I better start living in 60fps after this to move forward...
Thank you again for your time
@UncleRJ I should have added some more clarification in my original comment. The reason that the old version achieved 90fps is because double vsync would end up repeating each unique frame twice. So 1 frame would be displayed 2 times making the 45fps show as 90fps.
@Blisto91 correct me if I'm wrong but does this mean this whole time I never really achieve 90fps and that I was playing technically in 45fps? So playing in Proton 8.0-5 is a moot point...
Thank you for the clarification! I guess this has solved the issue.
That is my understanding yes (tester not a dev, but I asked to make sure)
@Blisto91 Thank you for taking time to test out this issue!
With update 1.10.1 (from 25 Dec.25), the game has some anti cheat updates that make it fail with recent proton versions. For me it now works only with "Legacy runtime 1.0"
Just found a solution on my pc (24.feb.2026):
I'm on BigLinux with kde plasma 6.5.5 and using heroic game launcher.
For starting successfully the game i tried many setups, and the working one is:
I need to test my logitech G25 but at the moment with xbox 360 controller game running smooth with ultra quality settings enabled on graphics (dependig on your pc hardware)
Game version is v1.10.1
Hope this can help! Enjoy!
proton 8.0-5x2 2024-12proton 9.0-3x3 2024-12proton 9.0-4x3 2024-12
Compatibility Report
System Information
I confirm:
Symptoms
CarX Street PC is less optimized on Proton 9.0-4 compared to Proton 9.0-3. I have lost about 45fps while keeping all settings unchanged. I cannot even reach past 60fps unless I disable frame limit, and even then it hovers around 83fps and dips below 70fps during gameplay. The fps shoots up when paused, though.
Reproduction
(I am guessing I put the game settings here?)
I'd say the only meaningful impact the settings can give is under Video settings, so here are my settings
Vertical synchronization: DOUBLE
Screen: WINDOWED
Resolution: 1152X720
Max frame rate: 90
Graphics quality: LOW
Shadow quality: MEDIUM
Anti-aliasing: FXAA
Motion blur: ON
Advanced smoke: OFF
Your car's smoke density: 1
Rival cars' smoke density: 0
Using above's settings had set me a stable 90fps during offline mode and not playing with other players in Proton 9.0-3. There are very brief frame drops here and there and the game stutters when you unpause but 90% of the time it stays at 90fps. To achieve 80fps in Proton 9.0-4, I need to set Vertical Synchronization to "OFF" and disable frame limit on Steam Deck's Performance menu, but this is unstable as the fps can drop down below 70fps occasionally. If I keep Vertical Synchronization to DOUBLE and enable frame limit, I would only get 45fps. Setting Vertical Synchronization to OFF while still enabling frame limit, I would get 60fps.