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{"bugs":[{"component":"Graphics","creation_time":"2017-02-22T23:15:05Z","id":1341913,"keywords":["perf"],"last_change_time":"2025-04-24T15:29:17Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"ASSIGNED","summary":"Stop looking up GLContext symbols for every new window"},{"component":"Performance: Navigation","creation_time":"2019-01-23T21:52:44Z","id":1522282,"keywords":["perf:pageload"],"last_change_time":"2025-03-21T02:42:31Z","op_sys":"Android","priority":"P1","severity":"S3","status":"ASSIGNED","summary":"Delayed image loading on low end ARM devices"},{"component":"Graphics","creation_time":"2020-04-21T20:52:29Z","id":1631949,"keywords":["perf:startup"],"last_change_time":"2022-10-12T00:08:45Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"ASSIGNED","summary":"Investigate merging shader cache files"},{"component":"Graphics: Text","creation_time":"2026-01-05T20:54:42Z","id":2008619,"keywords":["meta"],"last_change_time":"2026-07-21T18:25:48Z","op_sys":"Unspecified","priority":"--","severity":"S2","status":"ASSIGNED","summary":"[meta] Text shaping word cache affects performance on several SP3 tests (particularly TipTap)"},{"component":"Bookmarks & History","creation_time":"2009-04-01T20:00:41Z","id":486378,"keywords":["blocked-ux","perf"],"last_change_time":"2023-05-16T02:23:47Z","op_sys":"Windows Vista","priority":"P3","severity":"S3","status":"NEW","summary":"Poor performance using bookmarks menu with large amounts of bookmarks."},{"component":"Places","creation_time":"2009-04-29T22:35:30Z","id":490714,"keywords":["main-thread-io","meta","perf","perf:frontend","perf:responsiveness"],"last_change_time":"2025-03-11T07:58:22Z","op_sys":"All","priority":"P3","severity":"N\/A","status":"NEW","summary":"[meta] Implement an Asynchronous API for opening container query nodes"},{"component":"Layout: Columns","creation_time":"2010-06-29T14:36:04Z","id":575614,"keywords":["perf","perf:responsiveness","testcase"],"last_change_time":"2022-10-10T22:59:55Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"{inc} Resizing window is slow for long list with multicol (from \"-moz-column-count: 3\" or \"column-width: 20em;\")"},{"component":"XPConnect","creation_time":"2010-11-19T15:34:28Z","id":613498,"keywords":["perf","perf:pageload"],"last_change_time":"2025-03-11T08:46:07Z","op_sys":"macOS","priority":"--","severity":"S3","status":"NEW","summary":"Very slow chrome to content DOM access"},{"component":"Widget","creation_time":"2011-03-31T18:37:55Z","id":646937,"keywords":["perf","perf:resource-use"],"last_change_time":"2022-10-10T23:24:13Z","op_sys":"Linux","priority":"P3","severity":"S3","status":"NEW","summary":"throttle animation in completely obscured windows (virtual desktop, minimised, hidden behind other fullscreened windows)"},{"component":"Places","creation_time":"2011-06-02T18:09:59Z","id":661590,"keywords":["perf","perf:responsiveness"],"last_change_time":"2025-09-29T14:01:38Z","op_sys":"All","priority":"P3","severity":"S3","status":"NEW","summary":"Repeated calls to location.hash = \"#foo\" cause large amounts of disk activity"},{"component":"Graphics: WebRender","creation_time":"2011-12-19T09:05:20Z","id":711924,"keywords":["perf","perf:resource-use"],"last_change_time":"2024-04-08T16:58:41Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"Compositing\/present still hapens when the only changing parts are out of the viewport"},{"component":"Graphics: Canvas2D","creation_time":"2012-06-03T03:18:54Z","id":760888,"keywords":["perf"],"last_change_time":"2024-04-05T11:37:58Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"IE10 Test Drive: ParticleAcceleration Canvas 2D demo is slow"},{"component":"Networking","creation_time":"2012-10-19T21:25:22Z","id":803709,"keywords":["perf:resource-use"],"last_change_time":"2023-06-05T16:31:57Z","op_sys":"All","priority":"P3","severity":"S3","status":"NEW","summary":"We appear to be copying large data URIs over and over in nsSimpleURI."},{"component":"PDF Viewer","creation_time":"2012-11-09T08:29:30Z","id":810214,"keywords":["perf:responsiveness"],"last_change_time":"2025-03-31T14:05:54Z","op_sys":"Linux","priority":"P3","severity":"S3","status":"NEW","summary":"Processing http:\/\/lib.tkk.fi\/Dipl\/2002\/urn007413.pdf is slow, and its text layer is all messed up"},{"component":"CSS Parsing and Computation","creation_time":"2012-12-14T13:46:12Z","id":821693,"keywords":["perf","perf:responsiveness"],"last_change_time":"2023-03-01T12:04:23Z","op_sys":"Windows 7","priority":"--","severity":"S3","status":"NEW","summary":"janky Scrolling on smartsheet.com Sheets"},{"component":"Graphics: ImageLib","creation_time":"2013-01-07T19:06:03Z","id":827440,"keywords":["perf"],"last_change_time":"2022-11-24T06:34:31Z","op_sys":"Windows 7","priority":"--","severity":"S3","status":"NEW","summary":"nsIconChannel::AsyncOpen can block"},{"component":"Layout","creation_time":"2013-01-08T19:17:33Z","id":827937,"keywords":["perf"],"last_change_time":"2022-10-29T12:12:42Z","op_sys":"Windows 8","priority":"--","severity":"S3","status":"NEW","summary":"Opening huge mercurial long commit page freezing Firefox"},{"component":"SQLite and Embedded Database Bindings","creation_time":"2013-01-14T22:07:19Z","id":830504,"keywords":["perf:frontend","perf:responsiveness"],"last_change_time":"2024-08-20T19:28:43Z","op_sys":"All","priority":"P3","severity":"S3","status":"NEW","summary":"Firefox should abort on tryserver when executing SQL on the main thread"},{"component":"General","creation_time":"2013-02-05T02:16:08Z","id":837989,"keywords":["main-thread-io","perf:frontend"],"last_change_time":"2023-05-16T02:22:53Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"Use IOUtils for gLastOpenDirectory"},{"component":"Networking: File","creation_time":"2013-04-16T15:29:21Z","id":862383,"keywords":["main-thread-io","perf:responsiveness"],"last_change_time":"2024-03-27T16:10:09Z","op_sys":"macOS","priority":"P3","severity":"S3","status":"NEW","summary":"nsFileChannel::nsFileChannel causes expensive lstats"},{"component":"Networking","creation_time":"2013-07-07T15:57:11Z","id":890712,"keywords":["main-thread-io","perf","perf:frontend"],"last_change_time":"2024-04-01T16:26:36Z","op_sys":"All","priority":"P3","severity":"S3","status":"NEW","summary":"nsIOService::NewFileURI is doing main thread IO and causes jank"},{"component":"Layout","creation_time":"2013-09-10T12:49:00Z","id":914595,"keywords":["perf"],"last_change_time":"2023-07-27T07:06:57Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"Polygon.com page scrolling becomes extremely slow after a while"},{"component":"General","creation_time":"2013-09-17T02:34:03Z","id":917090,"keywords":["perf:resource-use"],"last_change_time":"2022-10-11T01:07:35Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"Visibility state is not updated when the browser window is obscured or on another workspace"},{"component":"Layout","creation_time":"2014-03-18T00:14:52Z","id":984690,"keywords":["perf"],"last_change_time":"2025-12-02T04:57:52Z","op_sys":"Linux","priority":"--","severity":"S3","status":"NEW","summary":"Optimize GetRootPresContext() to avoid going through the viewmanager \/ view tree"},{"component":"Toolbars and 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Controls","creation_time":"2015-01-06T01:55:10Z","id":1118086,"keywords":["multiprocess","perf","perf:responsiveness","testcase"],"last_change_time":"2025-12-05T02:06:49Z","op_sys":"All","priority":"P5","severity":"S3","status":"NEW","summary":"[e10s] There is a delay for about 1 seconds to display <select> drop-down list with 1600+ items"},{"component":"JavaScript Engine","creation_time":"2015-04-15T23:32:29Z","id":1154987,"keywords":["meta","perf"],"last_change_time":"2026-04-07T07:26:45Z","op_sys":"Windows 8.1","priority":"--","severity":"S3","status":"NEW","summary":"[Meta] Move JS parsing off of main thread and enable incremental parsing"},{"component":"Graphics: WebRender","creation_time":"2015-04-16T18:22:07Z","id":1155307,"keywords":["perf:animation","perf:responsiveness","reproducible"],"last_change_time":"2024-04-02T23:00:44Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"Very laggy panning and zooming of map on Orbis website"},{"component":"JavaScript: GC","creation_time":"2015-05-07T18:46:57Z","id":1162665,"keywords":[],"last_change_time":"2025-03-12T05:36:53Z","op_sys":"Unspecified","priority":"--","severity":"S3","status":"NEW","summary":"ES6 Map performance for large numbers of elements is deficient"},{"component":"DOM: Animation","creation_time":"2015-10-10T00:31:34Z","id":1213513,"keywords":["perf:responsiveness"],"last_change_time":"2023-02-19T05:13:03Z","op_sys":"Unspecified","priority":"--","severity":"S3","status":"NEW","summary":"2D canvas+HTML\/CSS animation demo site broken on Firefox, works great on Chrome"},{"component":"Layout","creation_time":"2015-10-23T09:20:20Z","id":1217748,"keywords":[],"last_change_time":"2024-09-22T12:08:26Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"On\/Off opacity changes shouldn't create active layers"},{"component":"JavaScript 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GC"},{"component":"Graphics","creation_time":"2016-06-29T13:06:59Z","id":1283089,"keywords":["perf:responsiveness","regression"],"last_change_time":"2022-12-08T15:45:06Z","op_sys":"Linux","priority":"P3","severity":"S3","status":"NEW","summary":"Firefox 40+ are very sluggish through x2go"},{"component":"Layout","creation_time":"2016-08-12T05:51:58Z","id":1294625,"keywords":["perf"],"last_change_time":"2026-06-10T12:53:35Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Try to tick refresh driver during html parsing"},{"component":"Layout","creation_time":"2016-08-18T03:04:45Z","id":1296161,"keywords":["perf"],"last_change_time":"2022-10-11T18:31:41Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Measure and solve sync reflow for studying gdoc performance."},{"component":"Widget: Win32","creation_time":"2016-10-01T23:51:50Z","id":1306925,"keywords":["perf"],"last_change_time":"2026-09-30T14:33:37Z","op_sys":"Windows 7","priority":"--","severity":"S3","status":"NEW","summary":"If you set a high Polling Rate USB port of the mouse (1000 Hz), there will be noticeable performance issues while moving tabs"},{"component":"Layout","creation_time":"2016-10-08T00:18:22Z","id":1308660,"keywords":["perf","perf:responsiveness"],"last_change_time":"2025-04-16T19:29:34Z","op_sys":"Unspecified","priority":"--","severity":"--","status":"NEW","summary":"for background tabs, break refresh driver tick into multiple events off the main thread's event loop"},{"component":"JavaScript Engine","creation_time":"2016-11-11T14:41:11Z","id":1316864,"keywords":["perf"],"last_change_time":"2022-10-11T18:44:06Z","op_sys":"Windows 10","priority":"P5","severity":"S3","status":"NEW","summary":"Google Apps extremely slow -- scrolling, updating text, etc -- unusable"},{"component":"Bookmarks & 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Layers","creation_time":"2017-01-27T21:15:19Z","id":1334655,"keywords":["hang","perf"],"last_change_time":"2022-10-11T18:58:09Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"PCompositorBridge::Msg_WillClose can block the UI thread when closing a window"},{"component":"Graphics","creation_time":"2017-02-22T22:05:51Z","id":1341882,"keywords":["perf"],"last_change_time":"2022-10-11T19:02:26Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Slow performance at drawing rectangles on Google Slides"},{"component":"Networking: HTTP","creation_time":"2017-02-25T04:45:01Z","id":1342632,"keywords":["perf"],"last_change_time":"2022-03-02T15:55:52Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Speed up PHttpChannelConstructor and consider streaming HttpChannelOpenArgs"},{"component":"Graphics: Layers","creation_time":"2017-02-28T23:07:56Z","id":1343383,"keywords":["perf"],"last_change_time":"2022-10-11T19:03:23Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"nsIDOMWindowUtils::StartFrameTimeRecording should not use sync IPC"},{"component":"Web Painting","creation_time":"2017-03-01T15:26:14Z","id":1343538,"keywords":["perf","perf:responsiveness"],"last_change_time":"2024-11-22T02:22:00Z","op_sys":"Unspecified","priority":"--","severity":"S3","status":"NEW","summary":"Overpainting on Google docs"},{"component":"JavaScript Engine: JIT","creation_time":"2017-03-10T12:17:59Z","id":1346178,"keywords":["perf"],"last_change_time":"2025-04-30T01:31:39Z","op_sys":"All","priority":"P3","severity":"S3","status":"NEW","summary":"Consider compiling Ion IC code less 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JIT","creation_time":"2017-03-21T09:28:43Z","id":1349148,"keywords":["perf"],"last_change_time":"2024-04-24T02:40:50Z","op_sys":"All","priority":"P3","severity":"S3","status":"NEW","summary":"Improve performance of megamorphic stubs"},{"component":"DOM: Service Workers","creation_time":"2017-03-24T15:40:46Z","id":1350367,"keywords":["perf"],"last_change_time":"2022-10-11T19:08:05Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Make service worker ScriptLoader paths use cached js bytecode from cache API"},{"component":"Session Restore","creation_time":"2017-03-25T15:19:03Z","id":1350569,"keywords":["perf:frontend"],"last_change_time":"2023-07-19T04:57:18Z","op_sys":"Unspecified","priority":"--","severity":"S3","status":"NEW","summary":"Avoid full session history collect for DOMTitleChanged\/OnHistoryReload"},{"component":"Audio\/Video: Playback","creation_time":"2017-03-25T21:49:47Z","id":1350618,"keywords":["perf"],"last_change_time":"2022-10-11T19:08:17Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Bad performance on Sony Horizon game page"},{"component":"General","creation_time":"2017-03-26T21:54:08Z","id":1350749,"keywords":["perf"],"last_change_time":"2022-10-11T19:08:21Z","op_sys":"Unspecified","priority":"--","severity":"S3","status":"NEW","summary":"Add some instrumentation to find commonly added preference observers"},{"component":"Performance: General","creation_time":"2017-03-29T17:44:37Z","id":1351755,"keywords":["nightly-community","perf","perf:resource-use","power"],"last_change_time":"2025-03-11T08:37:03Z","op_sys":"All","priority":"--","severity":"--","status":"NEW","summary":"Provide \"Slight\/Light\/Low power\/Battery saving\/Battery saver\" mode option"},{"component":"JavaScript: GC","creation_time":"2017-03-29T18:30:44Z","id":1351789,"keywords":["perf"],"last_change_time":"2025-04-27T11:43:06Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Add Telemetry probes for measuring garbage volume per GC"},{"component":"Layout","creation_time":"2017-03-29T20:02:58Z","id":1351829,"keywords":["perf"],"last_change_time":"2022-10-11T19:09:06Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"Consider faster alternatives to PLDHashTable in hot Layout code paths"},{"component":"Layout","creation_time":"2017-03-29T20:09:00Z","id":1351830,"keywords":["perf"],"last_change_time":"2025-05-05T12:26:28Z","op_sys":"All","priority":"--","severity":"S3","status":"NEW","summary":"Consider adding StyleDisplay() values to nsIFrame"},{"component":"Layout","creation_time":"2017-03-30T20:21:31Z","id":1352205,"keywords":["perf","perf:resource-use"],"last_change_time":"2026-10-05T20:09:40Z","op_sys":"Unspecified","priority":"P2","severity":"--","status":"NEW","summary":"Avoid running the refresh driver when the page is in background"},{"component":"JavaScript: GC","creation_time":"2017-03-31T19:02:50Z","id":1352524,"keywords":["meta","perf"],"last_change_time":"2025-05-06T16:14:08Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"[meta] Improve GC scheduling"},{"component":"JavaScript Engine: JIT","creation_time":"2017-04-04T14:54:51Z","id":1353384,"keywords":["perf"],"last_change_time":"2025-02-10T18:11:27Z","op_sys":"All","priority":"P3","severity":"S3","status":"NEW","summary":"Optimize GetName 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shutdown"},{"component":"Autocomplete","creation_time":"2017-04-14T09:29:21Z","id":1356532,"keywords":["perf:frontend","perf:responsiveness"],"last_change_time":"2024-03-22T08:25:52Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Try avoiding layout flushes in autocomplete::_handleOverflow"},{"component":"General","creation_time":"2017-04-14T16:14:15Z","id":1356594,"keywords":["perf:resource-use"],"last_change_time":"2022-10-11T19:12:20Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Rewrite AppConstants.jsm in C++"},{"component":"Tours","creation_time":"2017-04-19T11:50:56Z","id":1357710,"keywords":["perf","perf:frontend","perf:responsiveness"],"last_change_time":"2024-03-22T13:34:58Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Uninitializing UITour is expensive"},{"component":"JavaScript: GC","creation_time":"2017-04-19T16:33:44Z","id":1357810,"keywords":["perf","perf:responsiveness","triage-deferred"],"last_change_time":"2022-10-11T19:13:04Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Investigate source of memory_pressure event in gecko, and whether to repurpose it"},{"component":"JavaScript Engine: JIT","creation_time":"2017-04-19T20:51:47Z","id":1357884,"keywords":["perf"],"last_change_time":"2025-09-08T18:32:25Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Pre-generate and cache the most common optimized Baseline IC stubs"},{"component":"Inspector","creation_time":"2017-04-21T07:04:16Z","id":1358390,"keywords":["perf","perf:frontend","perf:responsiveness"],"last_change_time":"2023-03-15T12:20:36Z","op_sys":"Unspecified","priority":"P4","severity":"S3","status":"NEW","summary":"1.24ms uninterruptible reflow at 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one"},{"component":"Performance: General","creation_time":"2021-01-09T03:18:07Z","id":1685835,"keywords":["perf:resource-use","regression"],"last_change_time":"2025-05-23T13:44:28Z","op_sys":"Windows 10","priority":"P3","severity":"S3","status":"NEW","summary":"Too many tabs of one site can cause Firefox to lag"},{"component":"General","creation_time":"2021-01-18T20:44:14Z","id":1687376,"keywords":["perf:resource-use"],"last_change_time":"2022-10-11T23:58:11Z","op_sys":"Linux","priority":"P2","severity":"S3","status":"NEW","summary":"Large number of idle processes (with fork server enabled?)"},{"component":"Bookmarks & History","creation_time":"2021-01-21T20:44:06Z","id":1688073,"keywords":["perf","perf:frontend","perf:responsiveness"],"last_change_time":"2024-03-20T18:52:32Z","op_sys":"Unspecified","priority":"P3","severity":"S3","status":"NEW","summary":"Showing the bookmarks toolbar (Ctrl+Shift+B) janks the parent process for several seconds when there are many 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