KDE Plasma Wayland session using software rendering and is slow - va-api not working on nVidia

[TraceyC77]

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• [X] I have searched open bugs for this issue

Summary

When logged into Plasma Wayland, rendering is slow. It is unusable with an external monitor. There is a warning in the system tray that software rendering is in use

Steps to reproduce

Log into KDE Plasma with Wayland

Expected result

System is as responsive as with X11

Actual result

System is laggy, more so with an external monitor in use (laptop)

Environment

• [X] Is system up to date?

Repo

Unstable

Desktop Environment

Plasma

System details

Operating System: Solus 4.5 KDE Plasma Version: 5.27.10 KDE Frameworks Version: 5.115.0 Qt Version: 5.15.12 Kernel Version: 6.6.17-277.current (64-bit) Graphics Platform: X11 Processors: 16 × 11th Gen Intel® Core™ i7-11800H @ 2.30GHz Memory: 62.5 GiB of RAM Graphics Processor: NVIDIA GeForce RTX 3060 Laptop GPU/PCIe/SSE2 Manufacturer: Dell Inc. Product Name: XPS 17 9710

Other comments

Plasma Wayland had been very usable up until around June 2023. After an update, it became laggy. I hadn't reported this before because I had been doing testing of VAAPI / Firefox with Reilly and thought that might have affected things. Even after removing the vaapi package, however, the performance is still slow.

As a workaround I tried setting KWIN_DRM_USE_MODIFIERS=0 in /etc/environment as well as KWIN_DRM_USE_MODIFIERS=1 but saw no change in performance.

• Removed nvidia vaapi driver package, no change
• Switched to nvidia-beta driver, no change
• xeglgears crashes upstream mesa issue
• May be related to this closed issue 452219 in the KDE tracker

Possibly useful logs attached

logs_wayland_compositing.txt