Performance Triage

Nomination

Bugzilla

To (re)nominate a bug for triage, set the Performance Impact flag in Bugzilla to ?

This can be found by clicking Show Advanced Fields followed by Set bug flags when entering a new bug:

Or by expanding the Tracking section when editing an existing bug:

GitHub

To nominate a bug for triage, add the Performance label to an issue. This can be done by filing an new issue with the "Performance issue" template:

Or by opening an existing issue on GitHub and selecting the label from the right-hand bar:

Currently, only the following GitHub repositories are supported:

• fenix
• android-components
• focus-android

Queries

Performance triage

Full Query

ID	Summary	Status
1826576	CSS filter() with invert() and hue-rotate() results in sluggish scrolling on Wikipedia	NEW
1931717	[meta] High OOM rate and CC time in YouTube	NEW
1940667	30s of jank on parent-process doing something around getFixupURIInfo and ContentAreaDropListener.sys.mjs (resource://gre/modules/URIFixup.sys.mjs:278:18)	NEW
1941716	On a fresh profile, Negative heap-unclassified on "My Bugs" query on b.m.o	NEW
1942031	Bad canvas performance on this example (nokiadesignarchive.aalto.fi)	NEW
1943503	High CPU usage on Debian x64 bookworm (VMware player guest)	UNCONFIRMED
1950901	Testcase generating N=5K forms (using credential mgmt API?) takes 30s in parent-process and 50s in content process. Chrome takes 9s.	NEW
1958712	Testcase generating N <META> elements is 20x slower than Chrome and does weird stuff in Compositor and SceneBuilder (PAPZCTreeManager::Msg_UpdateZoomConstraints)	NEW
1959837	openstreetmap iD editor - slow zooming	NEW
1965718	Google Maps framedrops when I'm panning the map	UNCONFIRMED
1972941	[Linux] File downloading is CPU-intensive	NEW
1980812	Websites take way too long to load	UNCONFIRMED

12 Total; 12 Open (100%); 0 Resolved (0%); 0 Verified (0%);

Performance triage (pending needinfo)

Full Query

ID	Summary	Status
1771902	Compositor CSS animations are not paused in fully occluded windows	NEW
1925480	Fenix shouldn't use `nsToolkitProfileService` to identify a profile folder	NEW
1931716	Browser Kept Eating up RAM to the max, stopping the specific process in the task manager fix the issue temporarily.	UNCONFIRMED
1939354	RAM too much	UNCONFIRMED
1943419	Fluidd memory leak	UNCONFIRMED
1945665	airbnb.com - Attempting to enter a destination in the search by using the gboard causes the gboard to become unresponsive	NEW
1946248	Too much time spent in gfxMacPlatformFontList::DeprecatedFamilyIsAvailable during startup	NEW
1946913	Consume too much memory	UNCONFIRMED
1955509	Constant CPU usage while idle on the Tiki.org website front page	UNCONFIRMED
1957692	Testcase generating N=500 forms and submitting them takes 27s in both parent and content processes,and is 675x slower than Chrome (Part2 of bug 1950901)	NEW
1967585	Excessive memory allocation when toolbar icons are updated (e.g., during downloads or extension changes) — sometimes triggers OOM killer	UNCONFIRMED
1975272	Animated newtab background images consume CPU even when not in the foreground	NEW

12 Total; 12 Open (100%); 0 Resolved (0%); 0 Verified (0%);

Recently opened bugs with performance keywords in the summary

Full Query

ID	Summary	Status
1979242	Firefox on RISCV-64 fails to detect GPU and falls back to software rendering	UNCONFIRMED
1979325	Consider adding a Translations Snackbar Test for TranslationsTest	NEW
1979403	Stop using nsLayoutUtils::CompareTreePosition in AccessibleCaretManager	ASSIGNED
1979467	Unexpected memory usage with animated GIF	NEW
1979500	GPU process consuming CPU while Firefox not displayed on screen	UNCONFIRMED
1979506	High RAM memory usage in Firefox 141 (or memory leak)	UNCONFIRMED
1979560	on YouTube, audio and video not in sync anymore when fast forwarding for a while	NEW
1979587	Beta version works almost perfectly until you click the search field on the navigation bar.	UNCONFIRMED
1979594	[webgpu] Testcase creating n 1x1 canvases is 4x (N=5000) and 13x (N=50000) slower than Chrome	NEW
1979735	Testcase generating eTLD + N URL and opening it hangs the Parent-Process, and quickly uses 4GB+ RAM. Testcase hangs in Chrome too, but it uses about 200MB RAM only. For smaller N, Firefox is ~5x slower.	NEW
1979753	Firefox should implement WebGPU's adapter info bucketing	NEW
1979793	Firefox update while using causes max CPU utilization until restart	UNCONFIRMED
1979906	Memory leak detected when the user opens the app after closing a private custom tab flow	NEW
1979984	Investigate `webgpu:shader,validation,shader_io,size:size:*` regression from 2025-07-28 WGPU revendor	NEW
1980007	Firefox does not show Translator icon when a website is in "UI language"	NEW
1980138	Write some documentation about disassembling Firefox libraries, for performance or debugging	NEW
1980152	Perform bytecode encoding also in navigation cache, when finishing collecting delazifications	ASSIGNED
1980233	Issues in WebGPU CTS: `webgpu:api,validation,queue,copyToTexture,CopyExternalImageToTexture:destination_texture,sample_count:*`	NEW
1980264	Canvas randomization is too slow	NEW
1980485	Kotlin getInterfaceVTable is 1.68x slower in Ion vs Turbofan	NEW
1980488	Kotlin "org.jetbrains.skia.impl.register_$external_fun" is much slower than in V8	NEW
1980490	’kotlin.captureStackTrace is slower in SM than V8	NEW
1980491	kotlin.collections.copyInto_2507 is slower in SM than V8	NEW
1980528	Disable autoland for A11y perftests	NEW
1980660	Capture portal opens very slowly	UNCONFIRMED
1980677	Improve frame callback cancellation performance	NEW
1980685	Update WebGPU CTS to new version e0cb07691d8805a6285093d89e3738f1059b7d0c from 2025-07-30 19:44:27	NEW
1980757	Testcase writing from canvas to webgl and back to canvas in a loop continuously uses RAM and GPU memory (till OOM if not checked). Chrome uses constant memory (Part2)	NEW
1980767	Browser randomly freezing completely, then slowly turning black and white and then crashing moments later.	UNCONFIRMED
1980891	Elements of GPURenderPassDescriptor.colorAttachments and GPURenderPipelineDescriptor.fragment.targets should be nullable	UNCONFIRMED
1980922	Translate language recognition error on pdf viewer	UNCONFIRMED
1980991	Testcase writing from canvas to webgl and back to canvas in a loop continuously uses GPU memory (till OOM if not checked). Chrome uses constant memory (Part3)	NEW
1981029	Janky UX issues with PDF feature callouts	ASSIGNED
1981120	Add responsiveness to drag-to-pin promo card	ASSIGNED
1981274	utter-disappointment-with-firefox-performance	UNCONFIRMED
1981299	PerfStats beyond the first 32 are not collected from js/browsertime	NEW
1981314	www.bbc.com - The translation of the page is not done correctly	NEW
1981508	Update WGPU to upstream (week of 2025-08-04)	ASSIGNED
1981541	Firefox should enable wgpu-hal's `device_lost_panic` and `internal_error_panic` features only in Nightly	NEW
1981548	Poor performance on macOS	UNCONFIRMED
1981572	FinalizationRegistryObject::register_ is slow when registering lots of objects	NEW
1981590	`wgpu_hal::dx12::Device::check_if_oom` probably shouldn't be called when the device is lost	NEW
1981650	Testcase generating recursive scripts with document.write is 120x+ slower in Firefox (taking 16minutes +)	NEW
1981799	Testcase generating and registerin N MIME types is 20x slower in Firefox	NEW

44 Total; 44 Open (100%); 0 Resolved (0%); 0 Verified (0%);

Triage process

Introduction

The goal of performance triage is to identify the extent to which bugs impact the performance of our products, and to move these bugs towards an actionable state. The goal is not to diagnose or fix bugs during triage. We triage bugs that have been nominated for triage and bugs in the Core::Performance component that do not have the performance impact project flag set.

During triage we may do any/all of the following:

• Request further information from the reporter (such as a profile)
• Set the performance impact project flag
• Add performance keywords
• Move the bug to a more appropriate component

Who is responsible for triage?

Everyone is welcome to take part in triage. By default, everyone on the performance team is enrolled in triage rotation, but we also have participants from outside the team.

How do I schedule a triage meeting?

If you are on triage duty, you will receive an invitation as a reminder to schedule the triage meeting on the shared performance calendar with the nominated sheriffs invited at a time that works for them. The responsibility of scheduling the meeting falls to the lead sheriff. Once a triage meeting has been scheduled, it’s a good idea to remove the reminder event from the calendar to avoid confusion. It’s a good idea to use the shared calendar, as this increases the visibility of the performance triage and allows other members of the team to contribute or observe the process.

What if a sheriff is unavailable?

The rotation script is not perfect, and doesn’t know when people are on PTO or otherwise unavailable. If the lead sheriff is available, it is their responsibility to either schedule the triage with the remaining available sheriff or to identify a suitable substitute for the unavailable sheriff(s). If the lead sheriff is unavailable, this responsibility passes onto the remaining available sheriffs.

How do I run a triage meeting?

The following describes the triage process to follow during the meeting:

1. Ask if others would prefer you to share your screen. This can be especially helpful for those new to triage.
2. Open the first triage query to show bugs nominated for triage or in the Core::Performance component without the performance impact project flag set. The bugs are sorted from oldest to newest. For each bug in the list, follow these steps:
   • For defects: Determine if the bug is reproducible and actionable. If not, add a needinfo for the reporter asking for more information and move onto the next bug. We have a template that you can modify as needed.
   • For all bugs (including enhancements):
     • Set the performance impact project flag.
     • Add the appropriate performance keywords.
     • Move the bug to the correct Bugzilla component.
3. Open the second triage query to show bugs that have open needinfo requests. The bugs are sorted from oldest to newest. For each bug in the list, follow these steps:
   • If the needinfo was set less than 2 weeks ago, move onto the next bug.
   • If the needinfo was set more than 2 weeks ago but less than 2 months ago, consider adding a needinfo for either: another reporter of the issue, someone with access to the appropriate platform(s) to attempt to reproduce the issue, or a relevant subject matter expert.
   • If the open needinfo was set more than 2 months ago, close the bug as inactive. You can modify the inactive bug template as needed.
4. If time permits, open the third triage query to show recently opened bugs with performance related keywords in the summary. If any of these look like performance bugs, they can either be triaged the same way as bugs in the initial query or they can be nominated for triage in a subsequent meeting.

How do I determine the performance impact project flag?

The performance impact project flag is used to indicate a bug’s relationship to the performance of our products. It can be applied to all bugs, and not only defects. The triage calculator should be used to help determine the most appropriate value for this flag. In addition to setting the performance impact project flag, make sure to use the “Copy Bugzilla Comment” button and paste this as a comment on the bug.

How do I determine the performance keywords?

There are several performance related keywords, which can be helpful to understand how our performance issues are distributed, or whenever there’s a concerted effort to improve a particular aspect of our products. The triage calculator may recommend keywords to set, and by typing “perf:” in the keywords field in Bugzilla, you will see the available options. Select all that apply to the bug.

How do I determine the correct Bugzilla component?

Ideally we would only have bugs in the Core::Performance component that are the responsibility of the engineers in the performance team. For performance bugs to have the best chance of being fixed, it's important to assign them to the correct component. In some cases the correct component will be obvious from the bug summary, description, or steps to reproduce. In other cases, you may need to do a bit more work to identify the component. For example, if there's a profile associated with the bug, you could see where the majority of time is being spent using the category annotations.

Triage calculator

The Performance Impact Calculator was developed to assist in identifying and applying the performance impact project flag and performance keywords consistently. If you have feedback or would like to suggest changes to this tool, please share these in the #perf-triage Matrix channel.

Triage rotation

The sheriffs are allocated on a weekly basis, which is published here. The rotation is generated by this script.

Templates

New bug

This template is included in the description for new bugs opened in the Core::Performance component. If a bug is opened in another component and then moved to Core::Performance, this template can be used as needed to request additional information from the reporter.

### Basic information

Steps to Reproduce:


Expected Results:


Actual Results:


---

### Performance recording (profile)

Profile URL:
(If this report is about slow performance or high CPU usage, please capture a performance profile by following the instructions at https://profiler.firefox.com/. Then upload the profile and insert the link here.)

#### System configuration:

OS version:
GPU model:
Number of cores: 
Amount of memory (RAM): 

### More information

Please consider attaching the following information after filing this bug, if relevant:

 - Screenshot / screen recording
 - Anonymized about:memory dump, for issues with memory usage
 - Troubleshooting information: Go to about:support, click "Copy text to clipboard", paste it to a file, save it, and attach the file here.

---

Thanks so much for your help.

Moved to Core::Performance

This bug was moved into the Performance component. Reporter, could you make sure the following information is on this bug?

 - For slowness or high CPU usage, capture a profile with http://profiler.firefox.com/ , upload it and share the link here.
 - For memory usage issues, capture a memory dump from about:memory and attach it to this bug.
 - Troubleshooting information: Go to about:support, click "Copy raw data to clipboard", paste it into a file, save it, and attach the file here.

Thank you.

No longer able to reproduce

This bug doesn’t seem to happen anymore in current versions of Firefox. Please reopen or file a new bug if you see it again.

No response from reporter

With no answer from the reporter, we don’t have enough data to reproduce and/or fix this issue. Please reopen or file a new bug with more information if you see it again.

Expected behaviour

This is expected behavior. Please reopen or file a new bug if you think otherwise.

Website issue

According to the investigation, this is a website issue. Please reopen or file a new bug if you think otherwise.