** Changed in: mutter (Ubuntu Oracular)
Status: Triaged => Won't Fix
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https://bugs.launchpad.net/bugs/2105500
Title:
Low FPS on wayland when running dual monitors on laptop with Nvidia
GPU and iGPU
Status in mutter package in Ubuntu:
Fix Released
Status in mutter source package in Noble:
Triaged
Status in mutter source package in Oracular:
Won't Fix
Status in mutter source package in Plucky:
Fix Released
Bug description:
I have a Lenovo P16 Gen 2 laptop with both an NVIDIA GPU and an Intel
iGPU. I must say, Wayland sessions work phenomenally well—everything
feels incredibly smooth compared to my old Ubuntu 20.04 X11 sessions.
However, this changes the moment I plug in an external display. (For
context: my machine has two USB-C ports with DisplayPort support and
one HDMI port—all three are wired to the NVIDIA GPU, not the iGPU.)
When I connect an external display, it is detected immediately, but
the frame rate drops significantly on both the built-in and the
external screens.
I’ve tested different configurations: duplicating displays, extending
them, or using the external display only. In all cases, the frame rate
remains degraded. The only case where frame rates return to normal is
when I select only the built-in display.
What I’ve tried:
I’ve tested multiple GPU drivers, all in Wayland sessions. Based on
performance, this is the ranking I observed:
nvidia-driver-570 (with GSP firmware) < nvidia-driver-570 (without GSP
firmware, i.e., with Nvreg_EnableGpuFirmware=0) < nvidia-driver-570-open <
nouveau
The nvidia-driver-570-open performs noticeably better than the
proprietary version, but it still doesn’t match the performance of the
system without an external display connected.
Interestingly, when I open an X11 session with both displays
connected, there is no noticeable performance drop compared to using
the built-in display alone. So clearly, the FPS drop is specific to
Wayland.
Also worth noting: once I remove the external display, the Wayland
session becomes smooth again on the built-in screen. This reinforces
that the issue occurs only when an external display is actively in
use.
An interesting workaround:
In all scenarios where frame rates drop, enabling screen capture (e.g., via
OBS) causes the system to suddenly run at high FPS again—everything becomes
smooth. As soon as screen capture is disabled, the frame rate drops once more.
I discovered this workaround from [1].
Additional context and references:
Googling around, I’ve found that this seems to be a relatively common
issue (and likely not limited to Ubuntu 24.04.2). In particular, [3]
identifies what appears to be the same issue—related to mutter—and
proposes a “fix” that reportedly restores normal FPS behavior.
I’m including below a list of relevant discussions and bug reports.
Please note [3] in particular, which may contain a direct fix for this
problem.
Definitely related:
[1]
https://forums.developer.nvidia.com/t/frequent-lags-and-loss-of-smoothness-in-kde-plasma-with-dual-monitors-on-nvidia-3070-ti-wayland-x11/311888
[2]
https://discourse.gnome.org/t/wayland-external-monitor-refresh-rate-issue-nvidia-gpu/20652
[3] https://gitlab.gnome.org/GNOME/mutter/-/issues/3461
[4]
https://askubuntu.com/questions/1534213/wayland-on-4k-monitor-set-at-60-hz-feels-like-30-hz
Possibly related:
[5]
https://www.reddit.com/r/wayland/comments/168q67n/poor_performance_and_lags_on_nvidia_laptop_with/
[6] https://gitlab.gnome.org/GNOME/mutter/-/issues/3544
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: gnome-shell 46.0-0ubuntu6~24.04.8
ProcVersionSignature: Ubuntu 6.11.0-21.21~24.04.1-generic 6.11.11
Uname: Linux 6.11.0-21-generic x86_64
NonfreeKernelModules: socwatch2_16 vtsspp sep5 socperf3 pax
ApportVersion: 2.28.1-0ubuntu3.5
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Mon Mar 31 12:29:48 2025
DisplayManager: gdm3
InstallationDate: Installed on 2025-03-20 (11 days ago)
InstallationMedia: Ubuntu 24.04.2 LTS "Noble Numbat" - Release amd64
(20250215)
RelatedPackageVersions: mutter-common 46.2-1ubuntu0.24.04.6
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)
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