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{{DISPLAYTITLE:Performance Triage}}
{{DISPLAYTITLE:Performance Triage}}
{{message/box|If you have any feedback/suggestions/questions regarding the performance triage process, you can share them in {{matrix|perf-triage}}, or reach out to {{people|davehunt|Dave Hunt}} or {{people|frankd|Frank Doty}}.
= Nomination =
= Nomination =
== Bugzilla ==
== Bugzilla ==
Line 182: Line 185:


== What if things don't go as expected? ==
== What if things don't go as expected? ==
Don't panic! The triage process is not expected to be perfect, and can improve with your feedback. Maybe the result of the triage calculator doesn't feel right, or you find a scenario that's not covered in these guidelines. In this case we recommend that you bring it up in [https://chat.mozilla.org/#/room/#perf-triage:mozilla.org #perf-triage], or consider scheduling a short meeting with some triage leads (you can see some recent leads in the [[#Triage rotation|triage rotation]]). If in doubt, leave a comment on the bug with your thoughts and move on. There's a chance someone will respond, but if not the next performance triage sheriffs may have some other ideas.
Don't panic! The triage process is not expected to be perfect, and can improve with your feedback. Maybe the result of the triage calculator doesn't feel right, or you find a scenario that's not covered in these guidelines. In this case we recommend that you bring it up in {{matrix|perf-triage}}, or consider scheduling a short meeting with some triage leads (you can see some recent leads in the [[#Triage rotation|triage rotation]]). If in doubt, leave a comment on the bug with your thoughts and move on. There's a chance someone will respond, but if not the next performance triage sheriffs may have some other ideas.


== How do I determine the performance impact project flag? ==
== How do I determine the performance impact project flag? ==

Revision as of 11:16, 31 October 2023


{{message/box|If you have any feedback/suggestions/questions regarding the performance triage process, you can share them in #perf-triage, or reach out to Dave Hunt or Frank Doty.

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:

Bugzilla performance nomination on new bug form.png

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

Screenshot 2022-02-24 at 19.53.54.png

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:

Screenshot of file a "Performance issue" template on GitHub

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

Screenshot of adding a performance label on GitHub

Currently, only the following GitHub repositories are supported:

Queries

Performance triage

Full Query
ID Summary Status
1771902 Compositor CSS animations are not paused in fully occluded windows NEW
1777875 Lenovo Privacy Guard with "Enable this feature when typing passwords" causing excessive UI responsiveness delays (jank) 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
1966492 JS isn't minified in Fenix release builds NEW
1988776 MutationObserver's getReceiverFor is slow when there are a lot of observers NEW
1994817 Firefox CPU usage spikes to 100%+ on some sites, particularly when opening new tabs UNCONFIRMED
1999598 Firefox for macOS is using a lot of battery UNCONFIRMED
2005613 Opening the Suggest database on Android does a lot of IO (32MB read + 16MB write) NEW

16 Total; 16 Open (100%); 0 Resolved (0%); 0 Verified (0%);


Performance triage (pending needinfo)

Full Query
ID Summary Status
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
1972941 [Linux] File downloading is CPU-intensive NEW
1975272 Animated newtab background images consume CPU even when not in the foreground NEW
1982980 Memory leak in Firefox on Android when repeatedly appending and removing an iframe UNCONFIRMED
1988608 Tabs in Firefox refresh when multitasking UNCONFIRMED
1988762 Slow scrolling performance on particular sites (mastodon) NEW
1993778 Firefox causes MacBook battery to drain fast UNCONFIRMED

14 Total; 14 Open (100%); 0 Resolved (0%); 0 Verified (0%);


Recently opened bugs with performance keywords in the summary

Full Query
ID Summary Status
2003203 big performance disparity with Chromium on "figtree" font homepage UNCONFIRMED
2003226 riscv64: MacroAssembler::wasmCheckSlowCallsite doesn't account for `jal` sequence length ASSIGNED
2003310 The autocomplete text wiggles as you type "https://" possibly due to the forward-slash characters having special kerning/spacing rules applying and then not-applying and then applying again NEW
2003329 Open about:translations page from Translate QuickAction in Split View when enabled NEW
2003348 Consider adding a setting to perform originAttributes isolation on non-isolated sites with Fission NEW
2003677 [AI Window] [Insights] Performance Testing NEW
2003795 store.steampowered.com - GPU usage significantly increases causing performance issue NEW
2003817 Make MozURL memory reporting not double report NEW
2003879 [AI Window] [Semantic Search] Latency and Performance NEW
2003906 Create perftest to assess cost of subtree recration when CSS visibility on ancestor is changed NEW
2003963 [wpt-sync] Sync PR 56478 - classifies "translate" web feature NEW
2003977 A big difference in jank between Firefox and Chromium at 2025.holidayhackchallenge.com UNCONFIRMED
2004105 Enable WebGPU on Intel Macs NEW
2004125 Allow import of perfetto traces for android profiles NEW
2004157 Introduce cache memory statistics via XPCOM NEW
2004187 --enable-project=memory builds are broken ASSIGNED
2004397 Newtab frecency-based sorting RS data performance improvements NEW
2004471 Display Language Load Error Message in about:translations NEW
2004473 Display Unsupported Error Message in about:translations NEW
2004476 Ensure that the about:translations focus order is correct NEW
2004479 Ensure that the about:translations screen reader experience is correct NEW
2004546 UNABLE TO OPEN FIREFOX OR USE IT. Slow opening and I keep using troubleshooting UNCONFIRMED
2004564 Constantly growing `heap-unclassified` and memory usage on Debian Sid UNCONFIRMED
2004717 Add glean telemetry for QUIC slow_start_exited stat ASSIGNED
2004747 Performance of camerahandapp demo is bad in drawing mode NEW
2004775 [wpt-sync] Sync PR 56567 - [scoped-VT] Escape scroll-translation on scoped element NEW
2004895 TrueNAS 25.10.x memory leak when dashboard is visible UNCONFIRMED
2005026 Connect VPN bandwith usage with Fastly usage NEW
2005059 WebGPU: add immediate data API NEW
2005061 WebGPU: add transient color attachment (AKA transient texture) support NEW
2005065 WebGPU: support `texture-component-swizzle` feature NEW
2005093 WebGPU should not overload `ImplCycleCollectionTraverse` and `ImplCycleCollectionUnlink` for arbitrary `nsTArray<RefPtr<T>>` NEW
2005225 Full screen mode switch is slower with pinned tabs NEW
2005283 Is WebKit shaping 50x faster than Firefox? NEW
2005294 Update wgpu to upstream 500e2bae (2025-12-09) NEW
2005317 Implement PerformanceEventTiming targetSelector attribute NEW
2005341 7.8 - 7.04% damp jstracer.profiler-recording-performance.DAMP / damp jstracer.profiler-recording-performance.DAMP (Linux, Windows) regression on Mon December 1 2025 NEW
2005342 Regular massive memory leak UNCONFIRMED
2005365 Add inference performance metrics collection to llama.cpp runtime NEW
2005369 Add inference performance metrics collection to StaticEmbeddingsPipeline NEW
2005415 Evaluate scheduled vs lazy cleanup for AI Window Security Layer memory management NEW
2005428 Document WebGPU cycle collection macros ASSIGNED
2005459 99% tenuring rate on an artificial testcase that creates N Uint8Array(N). Firefox is 2x faster than Chrome though. NEW
2005489 Unify UDP code across Fast UDP I/O, NSPR, and MASQUE CONNECT-UDP NEW
2005572 Possible memory leak leaves computer unusable UNCONFIRMED
2005606 MASQUE proxy (HTTP/3) 56% slower than HTTPS proxy (HTTP/2) for 32MB file uploads on uploadtest.appspot.com (Windows) NEW
2005635 decathlon.fr website consuming CPU while not displayed UNCONFIRMED
2005702 Treat islamic-rgsa as an unknown calendar identifier NEW
2005791 Test storage initialization performance with old profiles NEW
2005792 Performance bug in redesigned synced tabs list composable NEW
2005801 Deeply-nested inline elements are slower to reflow in Firefox than in other browsers NEW
2005828 Mouseleave events do not fire for SVG elements when their display is set to 'none' until a user initiated mousemove is performed UNCONFIRMED

52 Total; 52 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:
    • Bugs that look like tasks that were filed by members of the Performance team will generally need to be moved to the Core::Performance Engineering component.
    • 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):
  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.

What if things don't go as expected?

Don't panic! The triage process is not expected to be perfect, and can improve with your feedback. Maybe the result of the triage calculator doesn't feel right, or you find a scenario that's not covered in these guidelines. In this case we recommend that you bring it up in #perf-triage, or consider scheduling a short meeting with some triage leads (you can see some recent leads in the triage rotation). If in doubt, leave a comment on the bug with your thoughts and move on. There's a chance someone will respond, but if not the next performance triage sheriffs may have some other ideas.

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.

For more information about what this flag, and it's settings mean see this blog post.

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.

How do I read a performance profile?

It's useful to be able to understand a profile generated by the Firefox Profiler, and hopefully someone in the triage meeting will be able to help. If you find an interesting profile, or just want to understand how to use them to analyse a performance problem, we encourage you to post a link to the profile (or bug) in #joy-of-profiling where someone will be happy to help. The profile may even be analysed during one of the regular "Joy of Profiling" open sessions that can be found on the Performance Office Hours calendar.

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.