Severe FPS drops triggered by mouse/keyboard input (also mapped with controller) after ~30 minutes of gameplay

[kaspychala]

Your system information

• Steam client version: 1745876290
• SteamOS version: 3.6.24
• Opted into Steam client beta?: No
• Opted into SteamOS beta?: No
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

After about 30 minutes of gameplay, any form of keyboard or mouse input (could be also mapped mouse / keyboard) causes a massive drop in performance — FPS drops for about 50% and CPU/GPU usage and wattage visibly fall in Performance HUD. As soon as I stop input (no keypress or movement), performance returns to normal. Rebooting the game fixes it temporarily.

A video showing same behavior can be seen in this Reddit post.

This happens in:

• Gaming Mode
• Desktop Mode
• With a mouse/keyboard
• With a Steam Deck with mapped mouse and keyboard
• With 8BitDo Ultimate controller (Bluetooth) with mapped mouse and keyboard
• With multiple Proton versions, including GE 9-27 and 8-25

Tried environment variables like WINEDLLOVERRIDES="winmm=n,b", LD_PRELOAD = "" and SDL_HINT_DISABLE_MOUSE_RELATIVE=0, but issue persists.

Example affected games:

• Schedule I
• Valheim

Steps for reproducing this issue:

1. Launch game on Steam Deck (e.g. Schedule I or Valheim)
2. Play for ~30 minutes with mouse and keyboard (or mapped mouse and keyboard)
3. FPS drops only when pressing keys, clicking, or moving camera/mouse
4. GPU/CPU usage and wattage drop when interacting — return to normal when idle
5. Restarting the game resets the behavior for another ~30 minutes

Additional observation:

In Valheim, using the mouse to move the camera causes FPS drops, but rotating the camera using the right joystick on a controller does not.

[matte-schwartz]

sounds like ValveSoftware/steam-for-linux#11446

you said LD_PRELOAD = "" didn't work, but that's probably because it expects it to be LD_PRELOAD= or LD_PRELOAD="" without any spacing between the = sign and the rest of the launch argument.

[kaspychala]

Okay, looks like I forgot to add %COMMAND% at the end of the launch parameters, which is why LD_PRELOAD="" didn’t work for me. I can now confirm that this method works — I played Schedule I for over 1.5 hours without any hiccups. Thanks @matte-schwartz for the link and the hint! 🫡

Hope Valve will finally address / fix this issue in next releases.

[ACheshirov]

I had the exact same issue with Fragpunk... It was so annoying that I had to restart the game every 20–30 minutes, especially if it happened during a ranked match.