I think the issues is more related to W7 and FF57 working well together. So what version of 7 32 or 64bit are you using and what FF57 32 or 64 bit are you using as this makes a difference.

I saw someone ask whether Firefox is unloading tabs when they become inactive for a while, perhaps as a more aggressive form of memory management. I have not heard that Firefox is doing that, but the behavior you observed implies something similar. Is there any kind of delay in showing the tab content after you switch, as though Firefox is reloading it from disk?

@WestEnd : I've updated the OP to answer your questions. I'm using the 64 bits version of Firefox on Win7 x64.

@Jscher2000 : I had this at some point (a centered loading gif when switching tab) but i can't confirm i had it in ff 57. I think it was in the previous version (56+). I'll try to be careful about this and see if it does it. For the context, i generally don't have more than 12-13 tabs. And generally if they're already loaded they will display just fine. But for the heavy sites the responsiveness will not be there. I just did a test with Tweetdeck. I opened the Network log and i switched from one tab to TweetDeck. It dislays fine, i try to click on a tweet to load the replies, no reply is displayed and 3 requests will stay in there not executed cf. image attached. A minute later, once all the cycle of taking a huge amount of CPU / RAM (like in the first image joined in the OP) is done, replies were loaded. The 3 requests stayed grey.

Try to disable accessibility services in Firefox.

• Options/Preferences -> Privacy & Security -> Prevent accessibility services from accessing your browser
• https://support.mozilla.org/en-US/kb/accessibility-services
• http://techdows.com/2017/08/firefox-57-prevent-accessibility-services-accessing-browser.html

@Cor-el : Cf. OP, i did without success regarding my issue.

jscher2000 said

I saw someone ask whether Firefox is unloading tabs when they become inactive for a while, perhaps as a more aggressive form of memory management. I have not heard that Firefox is doing that, but the behavior you observed implies something similar. Is there any kind of delay in showing the tab content after you switch, as though Firefox is reloading it from disk?

Little update. I was able to get what i talked about above : "a centered loading gif when switching tab". If i switch back and forth from one tab (any) to another one (heavy page like TweetDeck), i've it.

Also, on the 57.0.2, it seems the issue is a lot less impactful than it was. But this needs more time to confirm. I saw in the changelog : "Fix a regression with WebGL and D3D9 - Windows only", dunno if this may be related.

The fix for the Accessibility issue was in 57.0.1 and included in 0.2

This another way if using too much ram you can limit the processors that Firefox is using . You could try this please : Go the Menu then Tools --> Options --> Performance and untick everything. change the recommended size lower then see how it runs. Note: 0 = No Multi-processor = slow again. TRY 2 Restart Firefox after making these changes please.

Copy/Paste about:addons into the Address Bar and Enter.

Under Extensions which is right there top of the page Shows where your old addons are and Click. The names of them are there with a Blue Button, Click it. To try and find alternatives. Also this : https://mozilla.github.io/extension-finder/ just start typing.

Please let us know if this solved your issue or if need further assistance.

@Pkshadow : I did, but it seems similar to what i had with recommended parameters. Though i'm not sure you wanted me to disabled the hardware acceleration too ? I just unchecked the box to "use recommended parameters" and set it from 4 to 2. So, i still have this slowness and non-responsiveness when i switch to an heavy page like TweetDeck or a Twitch stream, but it's okayish so far. To be precise, it generally comes back responsive after up to 5s i'd say.

Regarding the RAM usage, with these CPU spikes it doesn't impact as much as before (and before it mainly did with these whole minute softlock), however i had to close Firefox at some point because it was taking 2.6 Go of RAM. I've 8 Go total so with a game opened it can be too limit. This amount of RAM used seems to hugely increase while watching Twitch streams. Dunno if there's a memory leak in the html5 video player. Otherwise i just opened Firefox some minutes ago and it currently takes a little more than 600 Mo.

I don't have Extensions that aren't compatible. I'm currently using Privacy Badger, HTTPS Everywhere, NoScript, GreaseMonkey, Stylish and AdBlockPlus. There's some overlapping but PrivacyBadger for instance does a little more than what NoScript can do.

I'd need a few days of testing still to be able to conclude on something, and testing both with 2 and 4 since from the latest update it's far better.

Glad 4 to 2 is working better. Maybe reduce down from 2 to 1

Can try things like Reduce the size of the trash can to something reasonable as it takes space and ram.

https://support.microsoft.com/en-us/help/15055/windows-7-optimize-windows-better-performance NOTE: The Last one Virtual Memory the 2 greyed out numbers go into the recommended size in both when tick. So Show 1 size

Each Extension you have give or take 20megs each

Actually there is no harm in disabling Hardware Acceleration as sometimes can do with out that and no issues, it also saves on GPU ram usage if low on that also. TEST is the best way .

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode If TEST in Safe Mode will find out what a bare bones uses.

No ...HTML5 Video chews through ram as Firefox has to processes it then turn it into music for the sound card.

You might want to consider moving to the Extended Release Version as 8megs is low in today's standards. 52.5.2 ESR. It will continue to get security updates until May 2018, and you can download and install it from this page: https://www.mozilla.org/en-US/firefox/organizations/all/ Note : Legacy Extensions will be deleted or removed in any version update after May 2018.

https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

You should make a backup of your Profile before going back and just because: https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

When Back in Normal Can disable all extensions and add back in 1 at a time and check Ram usage and decide if need that one or not full time on.

Please let us know if this solved your issue or if need further assistance.

@Pkshadow : "Glad 4 to 2 is working better." > There's a misunderstanding here. 4 or 2 seemed similar. I'm actually back to testing with the default 4 after i did with 2. The big improvement came with the Firefox update.

Thanks for the tip regarding the virtual memory, i increased it.

For the safe mode, i tried it before latest updates so i might try it again to see if i've similar slowness when i switch to some heavy pages.

8 Megs ? If i had 8 Mo of RAM i'd probably not be here :p. I've 8 Go which sure is now relatively low but still a supposed decent amount. FF57 is supposed to take less RAM but for now it takes as much / more for me. I tried ESR version and i had stranges issues with it, notably with Discord not displaying properly (fully grey page several seconds when switching server, etc.). But i still used it several days because NoScript wasn't released for Firefox 57 yet and even by checking "don't update", Firefox did switch to v57...

Anyway, testing default perf parameters, and i'll do a test in safe mode too. Expected result being it'll not be different that in normal mode, but who knows. Again thanks for the help so far. And i'll be sure to put this issue as solved if i don't see any huge slowness coming back after my tests (1 day or 2).

Seems like increasing virtual memory solved the problem. I only had 1 Go as a start value and 2 Go max. with 8 Go of physical RAM... Dunno why it was that low since by default it should be 8 Go RAM and 24 max.

Thanks o/.