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Bug 1773386 - Firefox Wayland uses higher CPU even at idle than Firefox X11 (and XWayland)
Summary: Firefox Wayland uses higher CPU even at idle than Firefox X11 (and XWayland)
Alias: None
Product: Fedora
Classification: Fedora
Component: firefox
Version: 31
Hardware: Unspecified
OS: Unspecified
Target Milestone: ---
Assignee: Gecko Maintainer
QA Contact: Fedora Extras Quality Assurance
Depends On:
Blocks: ffwayland
TreeView+ depends on / blocked
Reported: 2019-11-18 00:35 UTC by Mathew Robinson
Modified: 2020-11-24 16:29 UTC (History)
12 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2020-11-24 16:29:57 UTC
Type: Bug

Attachments (Terms of Use)

Description Mathew Robinson 2019-11-18 00:35:50 UTC
Description of problem:

When running Firefox as a wayland native application (as is default on Fedora 31) it consistently uses 15 - 30% CPU when idle. When being interacted with it uses significantly more CPU than the X11 version. This becomes a battery issue (which is how I noticed the problem)

Version-Release number of selected component (if applicable):
Name         : firefox
Version      : 70.0.1
Release      : 4.fc31
Architecture : x86_64
Size         : 269 M
Source       : firefox-70.0.1-4.fc31.src.rpm
Repository   : @System
From repo    : updates
Summary      : Mozilla Firefox Web browser
URL          :
License      : MPLv1.1 or GPLv2+ or LGPLv2+
Description  : Mozilla Firefox is an open-source web browser, designed for standards
             : compliance, performance and portability.

How reproducible: Run Firefox under Wayland observe CPU usage, Run Firefox with X11 observe less CPU usage.

Steps to Reproduce:
1. Run Firefox under Wayland

Additional info:

I'm not sure how to get a hard or consistent log that would be useful here. This is my observed behavior via htop. Happy to run diagnostics or collect any other logs that would be helpful.

Comment 1 Martin Stransky 2019-11-19 13:03:53 UTC
Can you get a gecko profiler addon ( and capture/share the profiling data?

Comment 2 Mathew Robinson 2019-11-19 15:12:14 UTC

Here is the profile data, I just moved the mouse around over top of the browser a bit, opened and closed a blank tab.

Comment 3 Martin Stransky 2019-11-20 07:44:49 UTC
Hm, I don't see anything wrong in the perf log, it just waits in g_main_context_dispatch.
Can you try to enable all possible threads in the profiler?

Comment 4 Mathew Robinson 2019-11-20 15:58:21 UTC


I've enabled all threads, I've also included XWayland profiler results for comparison.

I still see a 15 - 30% overhead in htop on the Wayland version of Firefox (it significantly effects battery life) 

Thanks for looking at this!

Comment 5 Martin Stransky 2019-11-26 12:48:08 UTC
Hm, I can't find anything wrong there.

Comment 6 Ben Cotton 2020-11-03 15:50:37 UTC
This message is a reminder that Fedora 31 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora 31 on 2020-11-24.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with a
Fedora 'version' of '31'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version' 
to a later Fedora version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora 31 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora, you are encouraged  change the 'version' to a later Fedora 
version prior this bug is closed as described in the policy above.

Although we aim to fix as many bugs as possible during every release's 
lifetime, sometimes those efforts are overtaken by events. Often a 
more recent Fedora release includes newer upstream software that fixes 
bugs or makes them obsolete.

Comment 7 Ben Cotton 2020-11-24 16:29:57 UTC
Fedora 31 changed to end-of-life (EOL) status on 2020-11-24. Fedora 31 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

If you can reproduce this bug against a currently maintained version of
Fedora please feel free to reopen this bug against that version. If you
are unable to reopen this bug, please file a new report against the
current release. If you experience problems, please add a comment to this

Thank you for reporting this bug and we are sorry it could not be fixed.

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