https://bugs.kde.org/show_bug.cgi?id=522924
Bug ID: 522924
Summary: Wayland: FPS drops and locks to 60 on 180Hz monitors
after closing Overview/Present Windows (Mixed refresh
rates + NVIDIA)
Classification: Plasma
Product: kwin
Version First 6.7.2
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: effects-overview
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
DESCRIPTION
On a Wayland session with a complex multi-monitor setup of mixed refresh rates
and an NVIDIA GPU, using global QML effects like "Overview" or "Present
Windows" causes the high-refresh-rate monitors to drop and lock to 60 FPS.
While the effect is active, KWin seems to sync the render loop to the lowest
common denominator (the 60Hz monitor) to avoid tearing. However, after the
effect is closed, KWin fails to release this lock. The 180Hz monitors stay
stuck at 60 FPS.
I am aware of Bug 485927 and the Qt 16ms timer fixes, but this issue is still
fully reproducible on the latest Plasma 6.7.2 and Qt 6.11.1.
STEPS TO REPRODUCE
1. Have a mixed-refresh-rate multi-monitor setup. My specific layout:
- Monitor 1: 1440p @ 180Hz (DisplayPort)
- Monitor 2: 1440p @ 180Hz (DisplayPort)
- Monitor 3: 1080p @ 60Hz (HDMI)
- Monitor 4: 720p PiKVM (DisplayPort, currently inactive)
* Adaptive Sync / VRR is OFF on all monitors.
2. Verify the primary monitors are rendering smoothly at 180 FPS.
3. Trigger the "Overview" or "Present Windows" effect.
4. Close the effect (press Esc or select a window).
5. Drag a window around or scroll on the 180Hz monitors.
OBSERVED RESULT
The 180Hz monitors feel stuttery, and the framerate is locked to 60 FPS
(matching the 60Hz monitor). The FPS remains stuck at 60 until a specific
screen update is forced (e.g., snapping a window to the screen edge, toggling
fullscreen with F11, or physically turning off the 60Hz monitor).
EXPECTED RESULT
The high-refresh-rate monitors should instantly return to 180 FPS and render
smoothly as soon as the Overview/Present Windows effect is closed.
SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 6.7.2
KDE Frameworks Version: 6.27.0
Qt Version: 6.11.1
Kernel Version: 7.1.2-zen3-1-zen (64-bit)
Graphics Platform: Wayland
ADDITIONAL INFORMATION
Processors: 24 × AMD Ryzen 9 9900X 12-Core Processor
GPU 1 (Primary): NVIDIA GeForce RTX 4060 Ti
GPU 2 (iGPU): AMD Radeon Graphics (Granite Ridge)
NVIDIA Driver Version: 610.43.02 (Proprietary)
Troubleshooting steps already taken:
- Setting `nvidia.NVreg_EnableGpuFirmware=0` does NOT fix the issue.
- Changing "Animation speed" to "Instant" in Plasma System Settings entirely
prevents the bug from happening, confirming that the issue occurs during the
KWin effect's animation rendering/sync phase.
- Disconnecting the 60Hz monitor completely prevents the bug.
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