Mouse stuttering triggered by keyboard input – affected keys change every launch

I would like to report a reproducible input-related stuttering issue that appears to be engine-side and not hardware-related.

While moving the mouse smoothly in Battlefield, pressing or releasing certain keyboard keys causes a noticeable stutter in mouse movement.

There are no FPS drops, no CPU or GPU usage spikes, and frametime appears stable. The stutter occurs exactly when a keyboard input event happens while the mouse is moving.

A critical detail is that each time the game is launched, different keyboard keys trigger the issue.

For example, in one launch the problem may happen with keys like U, 2, or 3. In the next launch it may happen with Right Control, Numpad Enter, or other unrelated keys. Some of these keys are not bound to any in-game action.

This forces multiple game restarts until none of the commonly used movement keys are affected.

After approximately 20 to 30 minutes of gameplay, the issue worsens. Mouse stuttering becomes more frequent, mouse movement can become inconsistent even without pressing keys, and the game can become completely unplayable. Restarting the game or rebooting the PC temporarily resolves the issue.

After a reboot, the problem does not reappear until the next long session or system shutdown.

Extensive troubleshooting has already been performed. Multiple keyboards from different brands have been tested, different USB ports were used, and mouse polling rates of 1000, 500, 250, and 125 Hz were tested. Hardware Accelerated GPU Scheduling was tested both enabled and disabled. SMT was tested on and off. Windows Fast Startup was disabled. GPU drivers were cleanly reinstalled using DDU. All overlays were disabled, including RTSS, MSI Afterburner, Discord, and Steam. No network optimization tools such as ExitLag were used. Timer resolution tools were tested on and off. USB power saving features were disabled. The issue does not occur in any other game.

Due to the random affected keys per launch, reproducibility, degradation over time, and independence from hardware or operating system configuration, this strongly suggests a Battlefield input handling bug. This may be related to keyboard event processing, input threads, or engine-level synchronization.

I am posting this to help consolidate reports and assist in identifying the root cause of this issue.