+++ This bug was initially created as a clone of Bug #1648998 +++

I chose to clone that one because it seemed almost identical to my bug. I wanted to add new information and impetus to solving it - I've put up with this issue for too long.
The "FirefoxCP Web Content" processes (typically around 8 run simultaneously) + "FirefoxCP WebExtensions" + Firefox itself = 4 to 8 GB of RAM usage, routinely. No other app I use ever exceeds ~ 1.2 GB! Clearly there is a major problem with Firefox's memory management.

+++ Re. Component: I selected "Memory Allocator", then noted the instruction "For reports about memory usage, please use the Firefox::Untriaged or Thunderbird::Untriaged component instead" - but there is no Component list entry for Firefox::Untriaged ! +++

Application Basics

Name: Firefox
Version: 81.0
Build ID: 20200917005511
Distribution ID:
Update Channel: release
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:81.0) Gecko/20100101 Firefox/81.0
OS: Darwin 19.6.0 Darwin Kernel Version 19.6.0: Thu Jun 18 20:49:00 PDT 2020; root:xnu-6153.141.1~1/RELEASE_X86_64
Multiprocess Windows: 1/1 Enabled by default
Remote Processes: 10
Enterprise Policies: Inactive
Google Location Service Key: Found
Google Safebrowsing Key: Found
Mozilla Location Service Key: Found
Safe Mode: false

Crash Reports for the Last 3 Days

Firefox Features

Name: DoH Roll-Out
Version: 2.0.0
ID: doh-rollout@mozilla.org

Name: Firefox Screenshots
Version: 39.0.0
ID: screenshots@mozilla.org

Name: Form Autofill
Version: 1.0
ID: formautofill@mozilla.org

Name: Web Compat
Version: 14.0.0
ID: webcompat@mozilla.org

Name: WebCompat Reporter
Version: 1.4.0
ID: webcompat-reporter@mozilla.org

Remote Processes

Type: Web Content
Count: 8 / 8

Type: Extension
Count: 1

Type: Privileged About
Count: 1

Add-ons

Name: Add to Buyee
Type: extension
Version: 4.4.0
Enabled: true
ID: @buyee-cart-extension

Name: Amazon.co.uk
Type: extension
Version: 1.3
Enabled: true
ID: amazon@search.mozilla.org

Name: Bing
Type: extension
Version: 1.2
Enabled: true
ID: bing@search.mozilla.org

Name: Chambers (UK)
Type: extension
Version: 1.0
Enabled: true
ID: chambers-en-GB@search.mozilla.org

Name: DuckDuckGo
Type: extension
Version: 1.1
Enabled: true
ID: ddg@search.mozilla.org

Name: eBay
Type: extension
Version: 1.2
Enabled: true
ID: ebay@search.mozilla.org

Name: Google
Type: extension
Version: 1.1
Enabled: true
ID: google@search.mozilla.org

Name: LastPass: Free Password Manager
Type: extension
Version: 4.56.1.3
Enabled: true
ID: support@lastpass.com

Name: Tree Style Tab
Type: extension
Version: 3.5.27
Enabled: true
ID: treestyletab@piro.sakura.ne.jp

Name: Video DownloadHelper
Type: extension
Version: 7.3.9
Enabled: true
ID: {b9db16a4-6edc-47ec-a1f4-b86292ed211d}

Name: Wikipedia (en)
Type: extension
Version: 1.1
Enabled: true
ID: wikipedia@search.mozilla.org

Name: Adobe Acrobat
Type: extension
Version: 18.0.2
Enabled: false
ID: web2pdfextension.17@acrobat.adobe.com

Name: GMarks
Type: extension
Version: 1.0.3.3.1-signed.1-signed
Enabled: false
ID: {A64F9D1E-FA5E-11DA-A187-6B94C2ED2B83}

Name: Imageshack-Clickberry Browser Add-on
Type: extension
Version: 2.1.3.1-signed.1-signed
Enabled: false
ID: jid1-2XvMEc6Luckz4w@jetpack

Name: Tab Utilities
Type: extension
Version: 1.5.28.1.1-signed.1-signed
Enabled: false
ID: tabutils@ithinc.cn

Name: Video Downloader professional
Type: extension
Version: 1.99.5
Enabled: false
ID: ffext_basicvideoext@startpage24

Name: Xmarks Bookmark Sync
Type: extension
Version: 4.5.0.8
Enabled: false
ID: foxmarks@kei.com

Name: YouTube HTML5 Switch
Type: extension
Version: v0.1.7.1-signed.1-signed
Enabled: false
ID: jid0-coCUQ7NySNPcj72dA3557kKXGZU@jetpack

Graphics

Features
Compositing: OpenGL
Asynchronous Pan/Zoom: wheel input enabled; scrollbar drag enabled; keyboard enabled; autoscroll enabled
WebGL 1 Driver WSI Info: CGL
WebGL 1 Driver Renderer: Intel Inc. -- Intel HD Graphics 4000 OpenGL Engine
WebGL 1 Driver Version: 4.1 INTEL-14.7.8
WebGL 1 Driver Extensions: GL_ARB_blend_func_extended GL_ARB_draw_buffers_blend GL_ARB_draw_indirect GL_ARB_ES2_compatibility GL_ARB_explicit_attrib_location GL_ARB_gpu_shader_fp64 GL_ARB_gpu_shader5 GL_ARB_instanced_arrays GL_ARB_internalformat_query GL_ARB_occlusion_query2 GL_ARB_sample_shading GL_ARB_sampler_objects GL_ARB_separate_shader_objects GL_ARB_shader_bit_encoding GL_ARB_shader_subroutine GL_ARB_shading_language_include GL_ARB_tessellation_shader GL_ARB_texture_buffer_object_rgb32 GL_ARB_texture_cube_map_array GL_ARB_texture_gather GL_ARB_texture_query_lod GL_ARB_texture_rgb10_a2ui GL_ARB_texture_storage GL_ARB_texture_swizzle GL_ARB_timer_query GL_ARB_transform_feedback2 GL_ARB_transform_feedback3 GL_ARB_vertex_attrib_64bit GL_ARB_vertex_type_2_10_10_10_rev GL_ARB_viewport_array GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_framebuffer_multisample_blit_scaled GL_EXT_texture_compression_s3tc GL_EXT_texture_filter_anisotropic GL_EXT_texture_sRGB_decode GL_APPLE_client_storage GL_APPLE_container_object_shareable GL_APPLE_flush_render GL_APPLE_object_purgeable GL_APPLE_rgb_422 GL_APPLE_row_bytes GL_APPLE_texture_range GL_ATI_texture_mirror_once GL_NV_texture_barrier
WebGL 1 Extensions: ANGLE_instanced_arrays EXT_blend_minmax EXT_color_buffer_half_float EXT_float_blend EXT_frag_depth EXT_shader_texture_lod EXT_sRGB EXT_texture_compression_rgtc EXT_texture_filter_anisotropic MOZ_debug OES_element_index_uint OES_fbo_render_mipmap OES_standard_derivatives OES_texture_float OES_texture_float_linear OES_texture_half_float OES_texture_half_float_linear OES_vertex_array_object WEBGL_color_buffer_float WEBGL_compressed_texture_s3tc WEBGL_compressed_texture_s3tc_srgb WEBGL_debug_renderer_info WEBGL_debug_shaders WEBGL_depth_texture WEBGL_draw_buffers WEBGL_lose_context
WebGL 2 Driver WSI Info: CGL
WebGL 2 Driver Renderer: Intel Inc. -- Intel HD Graphics 4000 OpenGL Engine
WebGL 2 Driver Version: 4.1 INTEL-14.7.8
WebGL 2 Driver Extensions: GL_ARB_blend_func_extended GL_ARB_draw_buffers_blend GL_ARB_draw_indirect GL_ARB_ES2_compatibility GL_ARB_explicit_attrib_location GL_ARB_gpu_shader_fp64 GL_ARB_gpu_shader5 GL_ARB_instanced_arrays GL_ARB_internalformat_query GL_ARB_occlusion_query2 GL_ARB_sample_shading GL_ARB_sampler_objects GL_ARB_separate_shader_objects GL_ARB_shader_bit_encoding GL_ARB_shader_subroutine GL_ARB_shading_language_include GL_ARB_tessellation_shader GL_ARB_texture_buffer_object_rgb32 GL_ARB_texture_cube_map_array GL_ARB_texture_gather GL_ARB_texture_query_lod GL_ARB_texture_rgb10_a2ui GL_ARB_texture_storage GL_ARB_texture_swizzle GL_ARB_timer_query GL_ARB_transform_feedback2 GL_ARB_transform_feedback3 GL_ARB_vertex_attrib_64bit GL_ARB_vertex_type_2_10_10_10_rev GL_ARB_viewport_array GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_framebuffer_multisample_blit_scaled GL_EXT_texture_compression_s3tc GL_EXT_texture_filter_anisotropic GL_EXT_texture_sRGB_decode GL_APPLE_client_storage GL_APPLE_container_object_shareable GL_APPLE_flush_render GL_APPLE_object_purgeable GL_APPLE_rgb_422 GL_APPLE_row_bytes GL_APPLE_texture_range GL_ATI_texture_mirror_once GL_NV_texture_barrier
WebGL 2 Extensions: EXT_color_buffer_float EXT_float_blend EXT_texture_compression_rgtc EXT_texture_filter_anisotropic MOZ_debug OES_texture_float_linear WEBGL_compressed_texture_s3tc WEBGL_compressed_texture_s3tc_srgb WEBGL_debug_renderer_info WEBGL_debug_shaders WEBGL_lose_context
Uses Tiling: true
Uses Tiling (Content): true
Off Main Thread Painting Enabled: true
Off Main Thread Painting Worker Count: 4
Target Frame Rate: 60
GPU #1
Active: Yes
Vendor ID: 0x8086
Device ID: 0x0166
RAM: 0

Diagnostics
AzureCanvasBackend: skia
AzureContentBackend: skia
AzureFallbackCanvasBackend: none
CMSOutputProfile: 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
Display0: 1440x900 scale:1.000000
DisplayCount: 1
TileHeight: 512
TileWidth: 512
Decision Log
HW_COMPOSITING:
available by default
OPENGL_COMPOSITING:
available by default
WEBRENDER:
opt-in by default: WebRender is an opt-in feature
WEBRENDER_QUALIFIED:
available by default
blocklisted by env: No qualified hardware
WEBRENDER_COMPOSITOR:
available by default
WEBRENDER_ANGLE:
opt-in by default: WebRender ANGLE is an opt-in feature
WEBRENDER_DCOMP_PRESENT:
opt-in by default: WebRender DirectComposition is an opt-in feature
OMTP:
available by default
WEBGPU:
disabled by default: Disabled by default
blocked by runtime: WebGPU can only be enabled in nightly

Media

Audio Backend: audiounit-rust
Max Channels: 2
Preferred Sample Rate: 44100
Roundtrip latency (standard deviation): ...
Output Devices
Name: Group
Multi-Output Device:
Apowersoft Audio Device: com.apowersoft.audioModelDevice
Headphones: builtin-external-mic|hdpn
Input Devices
Name: Group
Apowersoft Audio Device: com.apowersoft.audioModelDevice
Line In: AppleHDA:88

Enumerate database

Environment Variables

DISPLAY: /private/tmp/com.apple.launchd.0HcfOofxQh/org.macosforge.xquartz:0
MOZ_CRASHREPORTER_EVENTS_DIRECTORY: /Users/raybutler/Library/Application Support/Firefox/Profiles/knnp6cmg.default/crashes/events
MOZ_CRASHREPORTER_RESTART_ARG_0: /Applications/Firefox.app/Contents/MacOS/firefox
MOZ_CRASHREPORTER_RESTART_ARG_1: -foreground
MOZ_CRASHREPORTER_DATA_DIRECTORY: /Users/raybutler/Library/Application Support/Firefox/Crash Reports
MOZ_CRASHREPORTER_PING_DIRECTORY: /Users/raybutler/Library/Application Support/Firefox/Pending Pings
MOZ_CRASHREPORTER_STRINGS_OVERRIDE: /Applications/Firefox.app/Contents/Resources/browser/crashreporter-override.ini
MOZ_LAUNCHED_CHILD:
MOZ_CRASHREPORTER_RESTART_ARG_2:
XRE_PROFILE_PATH:
XRE_PROFILE_LOCAL_PATH:
XRE_START_OFFLINE:
XRE_BINARY_PATH:
XRE_RESTARTED_BY_PROFILE_MANAGER:

Experimental Features

about:home startup cache (browser.startup.homepage.abouthome_cache.enabled): false
Cookies: SameSite=Lax by default (network.cookie.sameSite.laxByDefault): false
Cookies: SameSite=None requires secure attribute (network.cookie.sameSite.noneRequiresSecure): false
Cookies: Schemeful SameSite (network.cookie.sameSite.schemeful): false
CSS: Constructable Stylesheets (layout.css.constructable-stylesheets.enabled): false
CSS: Pseudo-class: :focus-visible (layout.css.focus-visible.enabled): false
CSS: Masonry Layout (layout.css.grid-template-masonry-value.enabled): false
Developer Tools: Colour Scheme Simulation (devtools.inspector.color-scheme-simulation.enabled): false
Developer Tools: Compatibility Panel (devtools.inspector.compatibility.enabled): false
Developer Tools: Execution Context Selector (devtools.webconsole.input.context): false
Developer Tools: Service Worker debugging (devtools.debugger.features.windowless-service-workers): false
Graphics: Smooth Pinch Zoom (apz.allow_zooming): false
Media: AVIF (image.avif.enabled): false
Web API: Media Session API (dom.media.mediasession.enabled): false
Print Preview Redesign (print.tab_modal.enabled): false
Web API: beforeinput Event (dom.input_events.beforeinput.enabled): false
Web API: inputmode (dom.forms.inputmode): false
Web API: <link rel="preload"> (network.preload): false
Web API: WebGPU (dom.webgpu.enabled): false

Important Modified Preferences

accessibility.typeaheadfind.flashBar: 0
browser.cache.disk.amount_written: 198698
browser.cache.disk.capacity: 0
browser.cache.disk.filesystem_reported: 1
browser.cache.disk.hashstats_reported: 1
browser.cache.disk.smart_size_cached_value: 358400
browser.cache.disk.smart_size.enabled: false
browser.cache.disk.smart_size.first_run: false
browser.cache.disk.smart_size.use_old_max: false
browser.cache.disk.telemetry_report_ID: 3
browser.cache.frecency_experiment: 2
browser.contentblocking.category: standard
browser.download.useDownloadDir: false
browser.places.smartBookmarksVersion: 8
browser.search.region: IE
browser.sessionstore.max_tabs_undo: 20
browser.sessionstore.upgradeBackup.latestBuildID: 20200917005511
browser.startup.homepage_override.buildID: 20200917005511
browser.startup.homepage_override.mstone: 81.0
browser.startup.page: 3
browser.tabs.insertRelatedAfterCurrent.backup: true
browser.tabs.loadInBackground: false
browser.tabs.remote.autostart.2: true
browser.urlbar.matchBuckets: general:5,suggestion:Infinity
browser.urlbar.placeholderName: Google
browser.urlbar.placeholderName.private: Google
browser.urlbar.searchSuggestionsChoice: true
browser.urlbar.tipShownCount.searchTip_onboard: 4
browser.urlbar.userMadeSearchSuggestionsChoice: true
dom.apps.lastUpdate.buildID: 20161019084923
dom.apps.lastUpdate.mstone: 49.0.2
dom.apps.reset-permissions: true
dom.ipc.processCount.web: 4
dom.max_script_run_time: 0
dom.mozApps.used: true
dom.push.userAgentID: 883a8c41ac71410780ae8f5a9bddf255
dom.w3c_touch_events.expose: false
extensions.lastAppVersion: 81.0
font.internaluseonly.changed: true
font.language.group: x-western
font.minimum-size.ar: 9
font.minimum-size.el: 9
font.minimum-size.he: 9
font.minimum-size.ja: 9
font.minimum-size.ko: 9
font.minimum-size.th: 9
font.minimum-size.tr: 9
font.minimum-size.x-armn: 9
font.minimum-size.x-baltic: 9
font.minimum-size.x-beng: 9
font.minimum-size.x-cans: 9
font.minimum-size.x-central-euro: 9
font.minimum-size.x-cyrillic: 9
font.minimum-size.x-devanagari: 9
font.minimum-size.x-ethi: 9
font.minimum-size.x-geor: 9
font.minimum-size.x-gujr: 9
font.minimum-size.x-guru: 9
font.minimum-size.x-khmr: 9
font.minimum-size.x-knda: 9
font.minimum-size.x-mlym: 9
font.minimum-size.x-orya: 9
font.minimum-size.x-sinh: 9
font.minimum-size.x-tamil: 9
font.minimum-size.x-telu: 9
font.minimum-size.x-tibt: 9
font.minimum-size.x-unicode: 9
font.minimum-size.x-user-def: 9
font.minimum-size.x-western: 9
font.minimum-size.zh-CN: 9
font.minimum-size.zh-HK: 9
font.minimum-size.zh-TW: 9
gfx.blacklist.direct2d.failureid: FEATURE_FAILURE_DL_BLACKLIST_g984
gfx.crash-guard.glcontext.appVersion: 45.0.2
gfx.crash-guard.glcontext.deviceID: 0x0166
gfx.crash-guard.status.glcontext: 2
idle.lastDailyNotification: 1600862378
media.benchmark.vp9.fps: 198
media.benchmark.vp9.versioncheck: 2
media.gmp-gmpopenh264.abi: x86_64-gcc3
media.gmp-gmpopenh264.lastUpdate: 1572010994
media.gmp-gmpopenh264.version: 1.8.1.1
media.gmp-manager.buildID: 20200917005511
media.gmp-manager.lastCheck: 1600818296
media.gmp-widevinecdm.abi: x86_64-gcc3
media.gmp-widevinecdm.lastUpdate: 1582196620
media.gmp-widevinecdm.version: 4.10.1582.2
media.gmp.storage.version.observed: 1
network.cookie.prefsMigrated: true
network.predictor.cleaned-up: true
network.trr.blocklist_cleanup_done: true
places.database.lastMaintenance: 1600595704
places.history.expiration.transient_current_max_pages: 138214
plugin.disable_full_page_plugin_for_types: application/pdf
plugin.flash.arch: x86_64-gcc3
plugin.flash.blockliststate: 0
plugin.flash.desc: Shockwave Flash 32.0 r0
plugin.flash.lastmod_hi: 372
plugin.flash.lastmod_lo: 1842288515
plugin.flash.path: /Library/Internet Plug-Ins/Flash Player.plugin
plugin.flash.version: 32.0.0.433
plugin.importedState: true
plugins.ctprollout.cohort: test
plugins.ctprollout.cohortSample: 0.721562
print.print_bgcolor: false
print.print_bgimages: true
print.print_colorspace:
print.print_command:
print.print_downloadfonts: false
print.print_duplex: 1073741824
print.print_evenpages: true
print.print_footercenter: &PT
print.print_footerleft:
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print.print_margin_bottom: 0.5
print.print_margin_left: 0.5
print.print_margin_right: 0.5
print.print_margin_top: 0.5
print.print_oddpages: true
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print.print_paper_data: 0
print.print_paper_height: 11.00
print.print_paper_name:
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print.print_plex_name:
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print.print_resolution_name:
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print.print_scaling: 1.00
print.print_shrink_to_fit: true
print.print_to_file: false
print.print_unwriteable_margin_bottom: 17
print.print_unwriteable_margin_left: 17
print.print_unwriteable_margin_right: 17
print.print_unwriteable_margin_top: 17
privacy.cpd.cookies: false
privacy.cpd.downloads: false
privacy.cpd.formdata: false
privacy.cpd.history: false
privacy.cpd.sessions: false
privacy.popups.showBrowserMessage: false
privacy.purge_trackers.date_in_cookie_database: 0
privacy.sanitize.migrateClearSavedPwdsOnExit: true
privacy.sanitize.migrateFx3Prefs: true
privacy.sanitize.pending: [{"id":"newtab-container","itemsToClear":[],"options":{}}]
privacy.sanitize.timeSpan: 0
privacy.socialtracking.notification.counter: 2
privacy.socialtracking.notification.enabled: false
privacy.socialtracking.notification.lastShown: 1572365581670
privacy.userContext.enabled: true
privacy.userContext.extension: treestyletab@piro.sakura.ne.jp
privacy.userContext.longPressBehavior: 2
privacy.userContext.ui.enabled: true
security.remote_settings.crlite_filters.checked: 1600819380
security.remote_settings.intermediates.checked: 1600819380
security.sandbox.content.tempDirSuffix: {95d8a8a0-aace-6940-b5a2-4c3bb3aa67b0}
security.sandbox.plugin.tempDirSuffix: 0249a400-bcc0-054f-b360-aef6d18aa461
security.tls.version.enable-deprecated: true
services.sync.declinedEngines:
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services.sync.lastPing: 1525093694
services.sync.lastSync: Mon Apr 30 2018 17:11:39 GMT+0100 (IST)
signon.importedFromSqlite: true
signon.rememberSignons: false
signon.usage.hasEntry: true
storage.vacuum.last.index: 1
storage.vacuum.last.places.sqlite: 1600245656

Important Locked Preferences

fission.autostart: false

Places Database

Accessibility

Activated: false
Prevent Accessibility: 0

Library Versions

NSPR
Expected minimum version: 4.28
Version in use: 4.28

NSS
Expected minimum version: 3.56
Version in use: 3.56

NSSSMIME
Expected minimum version: 3.56
Version in use: 3.56

NSSSSL
Expected minimum version: 3.56
Version in use: 3.56

NSSUTIL
Expected minimum version: 3.56
Version in use: 3.56

Sandbox

Content Process Sandbox Level: 3
Effective Content Process Sandbox Level: 3

Startup Cache

Disk Cache Path: /Users/raybutler/Library/Caches/Firefox/Profiles/knnp6cmg.default/startupCache/startupCache.8.little
Ignore Disk Cache: false
Found Disk Cache on Init: false
Wrote to Disk Cache: true

Internationalisation & Localisation

Application Settings
Requested Locales: ["en-GB"]
Available Locales: ["en-GB","en-US"]
App Locales: ["en-GB","en-US"]
Regional Preferences: ["en-IE","en"]
Default Locale: "en-GB"
Operating System
System Locales: ["en-IE","en"]
Regional Preferences: ["en-IE","en"]

Mike, considering that you set it to Untriaged, can you say which other components it could belong to?
Or can you explain why you think it does NOT belong to the Memory Allocator component?

Thank you!

(In reply to Bodea Daniel [:danibodea] from comment #1)

Mike, considering that you set it to Untriaged, can you say which other components it could belong to?

If I could, I would have put it in that component.

Or can you explain why you think it does NOT belong to the Memory Allocator component?

Because memory usage issues are almost never memory allocator issues.
Also, comment 0 says:

Re. Component: I selected "Memory Allocator", then noted the instruction "For reports about memory usage, please use the Firefox::Untriaged or Thunderbird::Untriaged component instead" - but there is no Component list entry for Firefox::Untriaged !

Do you still see this issue now? If yes, please, I would like you to retry it after the update for Firefox 81.0.1 is made because some fixes will be introduced regarding some leaking windows while using certain addons.

Otherwise, you could tell us whether it still occurs when in safe-mode (without addons)?

Do you think we should close this?

Alternatively, do you think I should try to confirm it? In this case, I would need some more detailed steps to reproduce.

Considering the fact that the reporter hasn't answered in 3 months, do you think you could help me with some supposed steps that could confirm it? I'm not sure I understand what exactly I would need to do to attempt its confirmation.

Just install addons, try their features? How would it e best to measure used memory?

The Bugbug bot thinks this bug should belong to the 'Core::DOM: Content Processes' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Nothing in the memory report stands out as hogging an unusual amount of memory. A web browser using multiple GB of memory when loading multiple websites is common. Reddit is an especially heavy website.

How many GB of RAM do you have? We are working on Firefox tab unloading (bug 1587762) to improve these low memory situations.

I'm moving this bug to Firefox::Tabbed Browser component because that's the component of tab unloading bug 1587762.

What's the model ID of the Mac?

Firefox/81.0

Was that with a hard disk drive, solid state, or hybrid?

How are things now, with 113.0.2 and fission enabled by default?

With https://phabricator.services.mozilla.com/D105055, closed in 2021:

• if fission is enabled, the content process limit is no longer exposed in the GUI at about:preferences.

With fission, dom.ipc.processCount.webIsolated pref defaults to 4. Whilst this value may be reduced, beware: fewer processes (with less use of swap by Firefox) does not necessarily lead to a holistically more responsive system.

https://blog.mozilla.org/performance/

dom.ipc.processCount.webIsolated pref

Correction:

dom.ipc.processCount.webIsolated

Reporter, are you still experiencing this issue?

This bug was moved into the Performance component.

:ray.butler, 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.

If the requested information is already in the bug, please confirm it is recent.

Thank you.

Redirect needinfos that are pending on an inactive user to the triage owner.
:fdoty, since the bug has recent activity, could you have a look please?

For more information, please visit BugBot documentation.

Closing because we don't have enough information to move forward. Please file a new bug if you still see the issue.