Hello @Isaac-Clarke, we're using one issue report per unofficially supported game title, so I've gone ahead and transferred this issue report to https://github.com/ValveSoftware/Proton/issues/808#issuecomment-3046594891.
If this is the way it must be done,
then it's fine by me.
Just wanted to let it said here:
Until proper Proton from Valve implements NTsync, ProtonGE builds "are the fix" to this problem.
Performance should be 1-to-1 or higher than Windows...
proton 5.0-10x1 2025-07proton 7.0-6x1 2025-07DXVK_FRAME_RATE=400x1 2025-07DXVK_FRAME_RATE=400 %command%x1 2025-07
Compatibility Report
System Information
I confirm:
steam-212910.log
Symptoms
Long story short:
The GPU is not used properly by Proton, staying at a lower %. Changing MSAA setting does not raise nor lower performance (the FPS number stays the same AND the GPU% number doesn't rise), somewhat implying that MSAA has no issue working in this engine under Proton AND that it most probably is not the issue here.
Long story long:
My RTX 2070 PC still has Windows, so I can test things directly.
On Windows I reach 300+ FPS most of the times (on the same test map for testing consistency) and the GPU reaches close to 100% use, while the CPU stays too relatively high (like 60%+).
On Linux instead the framerate stays around 110, but NOT because "the system performs poorly under Proton", because the GPU's % is really low (the CPU's % seems to stay the same, more or less). The GPU stays around 40% use all the time, REGARDLESS if MSAA is off or at x8 {i made a mistake by assuming the issue on this other post, what I am saying here is the updated info that I now know}.
{Using Fedora KDE's Spectacle screenshot utility made the FPS go from 110 to 100, but everything else is the same, so just ignore the FPS number here.}
If I were to compare performance by doing X:Y=W:Z where X=?, Y=100%, W=110fps and Z=40%; I'd find that the performance of X (the FPS number when the GPU is at 100%, on Linux) would be 275fps, around 25fps less than Windows' at worse, which is expected, acceptable and maybe even normal
(many younger games perform almost 1-to-1 with Windows, at worse losing 10 fps, but it's expected because the development of Proton focuses on newer games first, older games can suffer a little because their base performances are already very good [usually in the 100s of fps]).
. . .
This happens on the other PC too, where the game is set at 720p Max, it stays at 70fps tho and the GPU% is around 55% (and leaving aside a bug which makes the game stutter when settings are changed during a game {because it's not what I want to focus on here, it can be tackled in the future}, THIS is the performance one would expect from such computer { these are basically the same, in regards of the important components } at 1080p, because on Windows at 720p the game stayed always above 110fps, usually around 130).
Reproduction
To reproduce this error/bug one has just to run the game.
In the past I managed to use Proton 5.0-10 on the GT 1030 PC, but now at least Proton 7.0-6 is needed to even successfully launch it on both PCs (most reliable way to "delete errors" is to uninstall and re-install the game and make it re-install its dependencies under the latest Proton you want to use).
The command
DXVK_FRAME_RATE=400 %command%works (put 400 because the PC should reach 300 easily) so it's not a "basic problem with syncing frames" (altho limiting it to 15 makes loading faster, go figure🤔).Except for a situational bug where "changing graphical settings while in a game makes the game bug out, rising CPU and GPU % to 100% and lowering performance under 20fps, which can be somewhat managed by juggling between fullscreen, borderless and window when changing settings each time (doesn't reliably work),
which at least for now has only happened on the other PC (OS is the same, components are I5-3470, 12gb DDR3, GT 1030, it can run DOOM 2016 almost as well as on Windows, therefore this Xbox 360 game is a piece of cake)
I'd say that this "lower GPU% use issue" is the only performance problem that CoD:BO2 has.