https://bugs.kde.org/show_bug.cgi?id=488403
Bug ID: 488403
Summary: KDE Plasma - Kwin_wayland Frame Rate limited to 60FPS
in Laptop(Single Monitor) Mode, Unexpectedly Renders
at 120FPS with External Monitor
Classification: Plasma
Product: kwin
Version: 6.0.5
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: compositing
Assignee: kwin-bugs-n...@kde.org
Reporter: curie64...@gmail.com
Target Milestone: ---
**Description:**
In KDE Plasma Wayland, kwin\_wayland's rendering for the desktop is limited to
a maximum of 60FPS in single monitor mode. This limitation can cause
framedrops, especially when the GPU is under load from other applications.
**Test Video:** [https://youtu.be/xVU9KCHwsgA](https://youtu.be/xVU9KCHwsgA)
**Unexpected Behavior:**
Connecting an external monitor, even a 60Hz monitor, can unexpectedly cause
kwin\_wayland to render at 120FPS. However, this behavior is not consistent and
should not be considered a solution.
**Impact on User Experience:**
The 60FPS rendering limit in single monitor mode can lead to:
* Framedrops
* Choppy animations
* Laggy scrolling
* Reduced responsiveness
**Test Environment:**
* **Operating Systems:**
* Debian (kernel 6.8.6) with Plasma 5 (5.27.5)
* Arch Linux (kernel 6.8.8) with Plasma 6 (6.0.5)
* **GPU:**
* Intel i7-8650U (HD620 graphics)
* **Displays:**
* **Laptop Display:**
* Model: Surface Book 2 15"
* Resolution: 3240x2160
* Refresh Rate: 59.995 Hz
* **External Monitor:**
* Connection: USB-C adapter and VGA cable
* Model Number: VS11234
* Resolution: 1400x1050
* Refresh Rate: 59.978 Hz
* H.frequency: 65KHz
* V.Frequency: 60Hz
* Pixel clock: 122MHz
**Test Scenarios:**
1. **Idle Desktop (Debian):**
* Observe kwin\_wayland rendering behavior and frame rate.
2. **Playing YouTube Video in Playing YouTube Video in Picture-in-Picture mode
(Arch Linux):**
* Observe kwin\_wayland rendering behavior and frame rate.
3. **Playing osu! Game (Arch Linux):**
* Observe kwin\_wayland rendering behavior, frame rate, and any performance
issues.
**Tools Used:**
* Plasma FPS monitor
* Intel\_gpu\_top (for monitoring GPU usage)
**Test Procedure:**
1. Connect the external monitor to the laptop.
2. Observe the frame rate, GPU usage, and any visual anomalies.
3. Disconnect the external monitor.
4. Observe the frame rate, GPU usage, and any performance changes.
5. Reconnect the external monitor.
6. Observe the frame rate, GPU usage, and any visual changes.
**Observations:**
* When the external monitor is connected, kwin\_wayland renders at 120FPS.
* Disconnecting the external monitor reverts kwin\_wayland to 60FPS rendering,
causing framedrops in all applications.
* Reconnecting the external monitor resumes 120FPS rendering.
**Tried Solution**
1. Restart
2. [Force to render 120FPS by modifying
\~/.config/kwinrc](https://www.reddit.com/r/kde/comments/ix3j51/applications_not_running_at_120hz_even_after/)
**Conclusion:**
The current behavior of kwin\_wayland limiting the frame rate to 60FPS in
single monitor mode, while unexpectedly switching to 120FPS with an external
monitor.
**Proposed Solution:**
* Allow kwin\_wayland to render at a higher frame rate in single monitor mode,
even if the display is only 60Hz. This would provide users with a smoother
visual experience and more control over their desktop performance.
**Further Explanation:**
The unexpected 120FPS rendering with an external monitor suggests kwin\_wayland
is capable of exceeding the 60FPS limit. A user-selectable option to raise the
frame rate cap would be beneficial.
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