Games Stutter Only When Moving the Mouse Diagonally

I've recently started having a strange issue in games: movement is smooth when I move the mouse horizontally or vertically, but the game stutters whenever I move it diagonally. Frame-time graphs remain completely flat during the stuttering, so it doesn't appear to be a normal FPS or frame-pacing problem. I've already tried reinstalling the graphics drivers with DDU, switching between my RTX 3080 and integrated graphics, using another monitor, reinstalling AMD chipset drivers, running SFC, changing USB ports, updating the BIOS, reinstalling USB drivers, refreshing the display driver, disabling fullscreen optimizations, toggling hardware-accelerated GPU scheduling, trying different peripherals, and disabling overlays. I've also tested four different mice, but the behavior remains the same. A clean Windows installation temporarily fixes the problem. However, after restarting the computer, the diagonal movement stutter returns—even when I prevent Windows from automatically installing drivers. System Restore does not resolve it either. What could cause this very specific input-related stutter? System specifications: - CPU: Ryzen 7 5800X3D - Memory: 16 GB Crucial Ballistix DDR4-3000 - GPU: Palit RTX 3080 10 GB - Motherboard: MSI MAG A520M Vector WiFi, BIOS A.L3 - PSU: Corsair TX650M