To see whether it could be related to the Flash Player plugin, try turning on "Click to Play" temporarily on the Add-ons page. Either:

• Ctrl+Shift+a
• orange Firefox button (or Tools menu) > Add-ons

In the left column, click Plugins. Then change the setting for Shockwave Flash from "Always Activate" to "Ask to Activate". If any site wants to use Flash, a notification icon will appear in the address bar. I'd wait to see whether CPU usage is high with Flash disabled before enabling it.

Thanks for the suggestions. That's something I hadn't considered, but it doesn't seem to have had any effect. Still hovering between mid-30s to 50% when I switch to the tab running the Facebook homepage.

Firefox uses too much memory or CPU resources - How to fix

I had previously tried most of the steps listed in that article.

I've never used themes.

All plug-ins are set to Never Activate except Shockwave (setting to Ask didn't help) and Acrobat (which is set to Ask).

The only add-on I had was AdBlock Plus.

I tried both Flashblock and NoScript, both did not help.

And hardware acceleration does not make a difference if on or off, currently it's off.

To update, I just went to the trouble of completely uninstalling, cleaning-up and reinstalling Firefox. I have Ad Block and Flash Player installed. Nothing else (and tested Facebook in Firefox before installing both of those). The issue STILL persists.

Please read this article and provide us with Some information, simply follow the steps and paste the information here.

Use the Troubleshooting Information page to help fix Firefox issues

Application Basics

Name: Firefox Version: 26.0 User Agent: Mozilla/5.0 (Windows NT 6.0; WOW64; rv:26.0) Gecko/20100101 Firefox/26.0

Extensions

Name: Adblock Plus Version: 2.4 Enabled: true ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}

Name: HP Smart Web Printing Version: 4.60 Enabled: false ID: smartwebprinting@hp.com

Name: Microsoft .NET Framework Assistant Version: 1.0 Enabled: false ID: {20a82645-c095-46ed-80e3-08825760534b}

Important Modified Preferences

browser.cache.disk.capacity: 358400 browser.cache.disk.smart_size.first_run: false browser.cache.disk.smart_size.use_old_max: false browser.cache.disk.smart_size_cached_value: 358400 browser.places.smartBookmarksVersion: 4 browser.sessionstore.interval: 300000 browser.sessionstore.upgradeBackup.latestBuildID: 20131205075310 browser.startup.homepage: https://www.facebook.com/ browser.startup.homepage_override.buildID: 20131205075310 browser.startup.homepage_override.mstone: 26.0 dom.mozApps.used: true extensions.lastAppVersion: 26.0 gfx.direct2d.disabled: true gfx.direct3d.last_used_feature_level_idx: 1 layers.acceleration.disabled: true network.cookie.prefsMigrated: true places.database.lastMaintenance: 1389662884 places.history.expiration.transient_current_max_pages: 104858 plugin.disable_full_page_plugin_for_types: application/pdf plugin.importedState: true plugin.state.npdeployjava: 0 plugin.state.npgoogleupdate: 0 plugin.state.npitunes: 0 plugin.state.npovshelper: 0 plugin.state.nppdf: 1 plugin.state.npqtplugin: 0 plugin.state.npvlc: 0 plugin.state.npwebsllauncher: 0 plugin.state.npwlpg: 0 plugin.state.npwpf: 0 privacy.sanitize.migrateFx3Prefs: true storage.vacuum.last.index: 0 storage.vacuum.last.places.sqlite: 1389662884

Graphics

Adapter Description: NVIDIA GeForce 9500M GS Adapter Drivers: nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um Adapter RAM: 512 Device ID: 0x0405 DirectWrite Enabled: false (7.0.6002.18392) Driver Date: 7-9-2010 Driver Version: 8.17.12.5896 GPU #2 Active: false GPU Accelerated Windows: 0/1 Basic Vendor ID: 0x10de WebGL Renderer: Google Inc. -- ANGLE (NVIDIA GeForce 9500M GS Direct3D9Ex vs_3_0 ps_3_0) windowLayerManagerRemote: false AzureCanvasBackend: skia AzureContentBackend: none AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0

JavaScript

Incremental GC: true

Accessibility

Activated: false Prevent Accessibility: 0

Library Versions

NSPR Expected minimum version: 4.10.2 Version in use: 4.10.2

NSS Expected minimum version: 3.15.3.1 Basic ECC Version in use: 3.15.3.1 Basic ECC

NSSSMIME Expected minimum version: 3.15.3.1 Basic ECC Version in use: 3.15.3.1 Basic ECC

NSSSSL Expected minimum version: 3.15.3.1 Basic ECC Version in use: 3.15.3.1 Basic ECC

NSSUTIL Expected minimum version: 3.15.3.1 Version in use: 3.15.3.1

You might consider installing and using Process Explorer to isolate exactly which process is hogging the CPU cycles.

I don't use Facebook, but "Facebook can cause a fair bit of cpu usage depending on the page you are on and size of friends list, feed wall and such." https://support.mozilla.org/en-US/questions/933514

If Flash is disabled, you might concentrate on JavaScript. You wrote that you used NoScript, but how? Did you temporarily block JavaScript for all sites?

I'm having the same problem with my FB newsfeed. I have 40+ FB groups that I've joined & my cpu % jumps up to 50+ % on my newsfeed or a group newsfeed. My profile page, messages, friends profiles the cpu % is 10 or less. I've tried the suggestions to fix & had no luck.

Facebook's own community help section seems to indicate others are having the issue, possibly in Internet Explorer as well, but not in Chrome.

It makes it hard to trouble shoot as it's obviously not isolated to one browser, but it's also not an issue with one of the top browsers.

So where is the problem? Is it a flaw in Firefox that it can't handle something the news feed is doing? Or is it a flaw in the news feed that Chrome has managed to avoid?

Either way it's a major annoyance and I'm tempted to switch to Chrome entirely.

Well, someone on Facebook's community help threads suggested adding a filter to AdBlock Plus:

facebook.com###leftCol div.rfloat

So far it seems to be working. It's not perfect, it still spikes a little bit here and there but it's nowhere close to the 50% that it was before.

It's not the solution I expected but I'm just glad it works.

I have been experiencing similar problems in using FF to access Facebook. When I load or click on a tab with my FB News Feed or any Group, my CPU usage rises to 80% to 95%. Any concurrent function on my machine slows down dramatically. Executing a video within the loaded FB display results in very sporadic operation. However, clicking on any FF tab containing any Facebook content other than a News Feed or Group (such as an individual's Profile) poses no problems.

I have tried all the suggestions above as well as completely removing FF and all its components and application data, and reinstalling it devoid of any extensions , without resolution. I also updated my video drivers. I have done this using both FF 24 and 26.

Interestingly, when I log onto Facebook using another account, the problem is not replicated. Returning to the first account brings a return of the problem. Facebook is apparently deploying new code designed to provide new functionality, including the automatic play of videos contained in posts. In doing so, Facebook typically rolls out new code by selected user group.

I am experiencing no problems in accessing and navigating Facebook with IE (other than IE's usual problems), Chrome or Opera.

Is it possible that the new code deployed to some but not all users is not compliant with FF?

@GregYorke - Adding the AdBlock Plus filter you mentioned did the trick for me as well. Many thanks! CPU usage for the FB News Feed is mostly back to normal.

It's more of a work around than a real solution of course since this problem doesn't happen in Google Chrome (my OS is Linux Mint 16) at all. This problem occurs with Firefox 26 with or without add-ons enabled, with Javascript, animated images and Flash disabled (heck, it even happens with CSS disabled so there's nothing but text on the screen). It really looks like it's a problem with Firefox itself.

Same problem for me... Firefox 27 on Ubuntu 13.10

I tried with the adBlock filter and by disabling the addon... it didn't make the trick.

You can try to disable JavaScript temporarily to check if this is an issue with a script running on that page.

• http://kb.mozillazine.org/JavaScript

The AdBlock trick worked after reboot the system... thanks!

Why id Firefox consuming so much more CPU cycles then the same (Facebook page) on other browsers? You may see the difference in this screen capture FF27 vs IE11 Is there another way to fix this then the AdBlock filter suggested before? This might maybe temporary fix the issue but who knows what problem it introduces for next?

I have two additions, that may or may not be relevant, given that my cpu is old and slow (Athlon XP at 540 MHz)

- chromium (!= chrome) shows the same problem, although less dramatically: it keeps the cpu at 100% for a long time; and sometimes sits idles for a short time.

- I painfully managed to run FF's profiler for several seconds, and it seems that most of the time is spent in long call chains in FB's javascript, very likely related with caching data for infinite scrolling.

The amount of JS that FB throws at browsers is impressive (lots of source files and lots of functions in each file), and I guess that some events are triggered by the server before previous event handlers have a chance to complete.

Perhaps FB's JS is really too demanding for old cpus, and the different behaviour between Chrome and FF can be explained in a slightly more efficient JS interpreter in the former, that saves it from ever-growing event queues.