• Firefox has become slow to open tabs

    • This topic has 54 replies, 8 voices, and was last updated 12 months ago.

    I can really use some help. Odd Firefox behavior.

    Been using Firefox forever. And the same way every day. Same way. Have a working group of 88 sites I open after starting Firefox. Usually takes 2-3 minutes tops for all to be readied. Now taking 10-12 minutes or more. Just last few days.

    I have three versions of Firefox. Right now main is 91.12 ESR which updated a few days ago. Also 91 ESR portable and 102.1 ESR Portable. All act the same. All used the same profile, copied from one to another.

    Things do change so I see that my ESET antivirus updated and could be it. Turning ESET off temporarily made no difference.

    Opening the session does use 100% CPU, but that is not new. Always has pegged. Comes down to normal when all opened. Single sites open as expected. And after all sites opened, FF acts as it always did with no issues. Its just loading all the tabs that is the issue.

    ODD Note: If I open the 91 ESR profile, then Startup Cache folder, clear the cache from about: Support, it does not delete the files. Yet that IS the profile being used. On at least one of the portables, that works as expected. If I delete the Startup cache files and open FF 91 ESR, it does not rebuild them. Makes me think it is using a different profile, but I am sure it is not.

    I cannot try Safe Mode as the Session Manager would not be there to open the saved session. I may try turning off some Add-ons to see if a conflict, maybe with something added or updated recently.

    Connection speeds have not changed and are above 400 Down and 150 Up.

    As mentioned, this has worked for years. Sometimes with as many as 120 tabs. So it has to be a recent change.

    I do have changes made to about:config but no idea where to try to make changes there to sleuth this issue. Happy to post the changed items, though long list.

    Can anyone help at all? Anything more I can tell you?

    Windows 10 latest build.

    Viewing 28 reply threads
    • #2469957

      Have a working group of 88 sites

      Have you checked each site for response tine (ping) ? May be some are slow to response slowing FF tabs loading ?

    • #2469982

      All used the same profile, copied from one to another.

      maybe that’s the problem.

      No problem can be solved from the same level of consciousness that created IT- AE
      1 user thanked author for this post.
    • #2469984

      Hi folks,

      Sorry to be tardy to respond. Been working through a few things to try with the Mozilla support (only one person replied there – no luck) and a Quicken problem today. No fun.

      I have tried remvong any slow loading site from the session. No change. Sites that open near instantly alone get caught up in the hgeneral issues.

      Does not seem to be a cache issue in either direction although BOTH disk and ram are enabled and nothing ever appears in the Cache2 folder.

      Since I posted here, other thoughts:

      Reinstalled the installed 91 ESR. No change.

      Disabled all addons except session manager. No change.

      Use Recommended and/or Use Acceleration make things much worse.

      This changed from working well for years to a slug about 48 hours agao. Not an addon issue. Windows? ESET?

      Appreciate the help and other suggestions. Its painful.


    • #2470013

      Create a new Profile, paste in the ‘old’ data that you really must have from a copied Profile folder on your Desktop, Mozilla/Mozillazine have recent walkthroughs – check that the filenames are correct against recently modified versions as there have been changes over the years.

      Refresh Firefox – reset add-ons and settings is worth a try first though.

      1 user thanked author for this post.
      • #2470160

        Or: If you have accumulated about:config tweaks
        (Do this offline for installed FFox)

        Copy prefs.js in FFox program files folder
        Backup bookmarks (as both HTML and .json – failsafe)
        Take note of your extensions.
        Remove existing profile and a new profile will be created when you open FFox.
        Once FFox is open leave it to create a new clean profile then close FFox.

        C&P prefs.js into appropriate program files FFox folder.
        Open FFox and import bookmarks.
        (once online) re-install the previously removed extensions.
        It’s a long winded method but I know it works for us when things occasionally go west with FFox. Been using this method for years without fail

        No problem can be solved from the same level of consciousness that created IT- AE
        1 user thanked author for this post.
        • #2470221

          Or: If you have accumulated about:config tweaks…Copy prefs.js…

          Call me slow on the uptake, but are all of our about:config tweaks stored in prefs.js??

          If so, that’s a real time saver versus going to Martin Brinkmann’s Ghacks detailed listings page for FF and going one by one through those listings to decide which ones you want to tweak all over again after many years!

    • #2470018

      Thanks. Appreciate that. And I can play all day long with the protable versions without fear, except that it seems since I am accessing though my computer it *might* place the new profile in my User/appdata/mozilla, etc profiles folder rather than in the profile folder of the portable. Sound true and like a risk?

      As long as any changes to a prtable version on my desktop does not affect the installed version, I would try both.


      • #2470029


        …And I can play all day long with the protable versions without fear, except that it seems since I am accessing though my computer it *might* place the new profile in my User/appdata/mozilla, etc profiles folder rather than in the profile folder of the portable. Sound true and like a risk?

        No, it’s not a risk. The portable versions of FF have their own profiles, completely separate from any other profile for FF that might exist on the computer. Each portable version of FF has its own profile stored in its own directory and it doesn’t “look around” the hard drive/SSD to see if there are any other profiles on it.

        The default location for the portable version’s profile is in its >data>profile directory. I used the > instead of a back slash because of this site’s unpredictable handling of back slashes, which is a known “bug” to the site’s managers (Susan, PK, et al.).

        So, if your copy of a portable version of FF is in the C:>FirefoxPortable directory (for example), then you will find its profile in the folder labeled C:>FirefoxPortable>Data>profile .

        As far as your performance issue with the slowness experienced in trying to load 88 separate sites upon being launched, I suspect that the root cause may very well be that your profile in each version has gotten a little long in the tooth, given that you say that you’ve been using it/them for years, AND the fact that you’ve replicated the profile amongst all three of your installations.

        So, do what @satrow suggests above in the last sentence of the post, and do a refresh of FF by following the instructions referred to in the link in that last sentence of the post. BONUS: It should allow you to keep all of your bookmarks at the end of the refresh on your fully installed version. That, in turn, will allow you to propagate them to the remaining two installations of the portable versions.

        I just did it to solve a sudden crash on reboot problem that I’d been having with a profile that was almost six years old. I performed the reset and then started tweaking the settings back to where they’d been before, and now I’m doing very well. The process also shrunk the number of files in the profile from 99 down so a more svelte 43. FF still works just like it had before, and is just as secure as it was before, but with a LOT less “baggage” in the profile.

        One final note: Your installation of FF91 ESR will be completely unsupported after September 20th because Mozilla is sunsetting FF 91 (no more updates of any kind at all for any reason) at that time. That will make FF 102 the new ESR default that will be supported with updates. Good to see you’ve got at least one installation of it! The last version of FF 91 ESR will be released on August 23rd, and will be FF 91.13 ESR. Between August 23rd and September 20th, only minor fixes or security updates that increase the version number by a .01 (91.13.01 for example) will be released for FF 91 ESR.

    • #2470034

      Thanks, but,

      “The portable versions of FF have their own profiles, completely separate from any other profile for FF that might exist on the computer. Each portable version of FF has its own profile stored in its own directory and it doesn’t “look around” the hard drive/SSD to see if there are any other profiles on it.”

      Actually not so. If you open about:profiles from portable it sees the profile from the installed version. It is not set as default, but it =knows its there and can be acted upon.

      It is possiblee its a profile issue. But bookmarks, passwords, extensions, settings, chrome, etc. Lots there. With 102 I copied over only what I had to to get all that including things like places.sqlite, etc. I may have to bite this bullet, but will not know until i test and play for a long time 🙂

      Appreciate all the thoughts.  Will try a few things in the morning….


      • #2470041

        …If you open about:profiles from portable it sees the profile from the installed version. It is not set as default, but it =knows its there and can be acted upon.

        Wow, did not know that.

        However, I’ve got three installations on my own computer and there are two installations on my wife’s computer of FF. Each computer has one fully installed version that is the daily driver. My wife’s computer has one installation of FF portable (always the latest in the Release channel) and my computer has two FF portable installations (both the latest in the Release channel).

        Although I’ve never tried going into about:profiles in any of the portable installations, I have made many frequent changes on and off to their profiles, and those changes have never affected the version that’s permanently installed on either machine. Same thing goes for the permanently installed versions…changes to their individual profiles have never made it into the portable profiles unless I went in and made the change(s) myself to the portable profiles. That’s why I said that they don’t go looking. I guess should change that to include “unless you make them look by going into the about:profiles page”.

        Hold on a sec, lemme look in my my permanently installed version on my computer to see if it can see any one of the portable installations’ profiles on my computer…and I’m back. No, it can’t see any of the profiles belonging to the portable versions of FF installed on my computer. It only saw profiles in the designated locations for profiles where they’d previously been in the past and where they are currently for the installed version.

        • #2470042

          Yup. Same for me. Inyteresting, though, isn’t it? Which is why I held off trying to change a prtable profile. But now, as you see, cannot find a refresh. It “feels” like it will help, albeit a lot of work. But will have to see.

    • #2470038

      Interesting. Just took a look and no Refresh Firefox button!



      • #2470045

        I just did some looking by quitting my permanent FF and starting both of my portable FF’s. They both produced the same about:profile results you did…they only see any profiles associated with the permanent installation, not the portable one.

        However, in the settings folder of the portable installation is a little file that tells the portable FF where to find the profile it needs in order to launch, and that file points the portable FF right to its own separate profile within its own directory, not the user profile directories maintained by Windows. That file only exists in a certain place within the portable versions, and it’s probably called by the “FirefoxPortable.exe” file that successfully launches the portable version(s). That .exe doesn’t exist at all in a normal permanent installation’s folders.

        When you type in about:profiles in the address bar, Firefox at that point takes over, and its programming is telling it to look in certain default location(s), based upon the installed OS it detects during its launch. Those default locations don’t include the special location of the portable installation at all.

        BTW, to get back to the main topic/your main question, I still think that you may very well benefit from doing a refresh as @satrow mentions. Your profile’s probably just long in the tooth and FF can no longer decently keep up with trying to launch so many sites at once.

        Remember, though, that the reset process will keep your bookmarks, so that’s one less thing to worry about having to re-establish.

        I’ve also discovered a nice way to restore your bookmarks from your old profile, if you need to, and it’s relatively easy. It’s done completely from within Firefox, using the Bookmarks Manager that’s built into FF.


        • #2470099

          Good morning. And thanks for the continued dialog.

          First, I use the bookmark tool all the time to backup and restore to other profiles. Works like a charm. But I do have 45 addons (I think) and setting those all up is work.

          HOWEVER!! Tried an experiment last night. Went into my system backups and restore a profile from 7/1/22 when things were just perfect. Put a 91 ESR portable on my desktop. Used that profile and….

          Same issue.

          So unless I am missing something, it cannot be profile related. Nor executable related asd three different share the same issue with sevral different profiles including one known working “just fine”.

          That being said, I’ll read the rest of your posts after this. But I have to start looking at other things.

          Was not a windows update since this started.

          WAS Eset AV update, but turning that off did not help. Perhaps a way to exclude  FF from it? There ARE new temp files called AdditionalThumbPrints.xml and Etag. This is an obvious place to look.

          MANY Edge updates, but I would not think they would affect FF unless something systemic.

          FF updates form 91.5 to 91.12, I should be able to find a portable to test that. Doubtful though.

          What else???

          My money is on ESET.

      • #2470046

        I didn’t refresh FF from within the browser at all, I used the option that shows up in the “Programs and Features” item in Windows’ old Control Panel.

        I launched Control Panel (NOT the “Settings” selection on the Start menu), then I clicked on “Uninstall a program” under the title in green that says “Programs”.

        At the time, I wanted to uninstall FF due to the problems I was having with it crashing on shutdown, so that’s why I clicked on the “Uninstall” option once I highlighted FF in the list of installed programs.

        BUT, then something different happened. I was asked if I really wanted to uninstall FF or to simply refresh it. In the box offering me that choice was wording that said that doing a refresh would make FF act as if I’d just installed it by changing all of its settings back to their default, but that it would KEEP my bookmarks.

        I took the refresh option that I was offered at that point, and it worked well. HOWEVER, I did have to go back into Tools>Settings and tweak everything back to my liking within FF. I also had to go back into the advanced settings page and tweak several of those settings as well, but I had the help of a fantastic article that’s on the Ghacks site for just such an event.

      • #2470047

        On the about:support page in my permanent installation of FF, I do have a “Refresh FF” button. Obviously I’m not about to click it because I don’t need to do so, FF’s working just fine. Lemme go check both of my portable FF installations and see what they produce with about:support. Be back in about 5 minutes.

      • #2470050

        I’m back, and on BOTH of my portable installations, about:support doesn’t show the Refresh FF button. So, they somehow know that a refresh of the installation is not possible. Probably got something to do with their startup routines that’s coded into the “FirefoxPortable.exe” file that I mentioned above in a prior post.

        That goes to show why, should you decide to do a refresh of FF, you should start with your permanent installation…it can be refreshed whereas the portable versions probably would have problems doing so.

        So, if you decide to go through with a refresh, start with your installed version and tweak it back to your liking fully. Then, copy that resulting profile’s folders and files to the profiles of your portable installations, and you should be good to go, hopefully with those 88 pages loading a lot faster than they do now.

        I gotta say, though, that 88 pages really seems like a tremendous amount of data to process simultaneously upon starting a browser, no matter which one it is, FF or otherwise.

        • #2470101


          I have had a startup session in FF of up to 120 pages and no issues. I do it all the time and for years and years. 2-3 minutes for all to load. Not like now being 5 times that long. So that is not an issue.

          I tested a 41 page session as well to check. Same slowness loading.

          Would not want to play that far with permanent install right now. Especially since older profile has the same issue.

          One more thing that changed is my chrome settings form Aris-T2 Classic for FF. But I disabled all that and no change, though I would not expect that to be the issue.


    • #2470096

      Very interestng discussion here. When I read this thread and went looking at my Fx installations, I found that my Fx 60.9 ESR installation is listed as the default profile and my Fx 91.12.0 ESR Portable shows no default profile but does show two profiles. I wonder if I did not have the 60.99 ESR installation at all but just the Portable ones if one of those would then show as default….probably not since they are from Portable Fx.

      My Fx 60.9 ESR offers refresh but the two Portable profiles do not.

      As for loading 88 tabs on Start, I routinely load about that many on both Portable and Regular Fx ESR. I only have 200 mbps down but they load quickly as that just restores the previous session.

      What I like about having an installed version and also a portable one is that I can easily run both simultaneously.

      • #2470103

        Totally agree. I and I used to have that experience 🙂

        I have to think “at this moment” its ESET. And not sure how to fix that.

        Not a defender user and ESET has always been great for me with email in Outlook Desktop and FF and HAS blocked dangerous stuff. But now with the slow load unsure what to do. Will need more coffee and some Googling.

        Appreciate all the help here, especiall bob99.

    • #2470114

      Running down more possibilties, to elimnate things:

      It is NOT the theme of choice. Default theme has the same issue.

      AdditionalThumbPrints.xml is a Lenovo file in temp. Possible but no mention of FF or Mozilla in the file, though this file in itself is curious. Seems Vantage made this and is new last few days. Could be an issue. Will try to disable vantage services and see if it helps.

      THIS could be interesting:

      An entity tag (ETag) is an HTTP header used for Web cache validation and conditional requests from browsers for resources.

      Etags use persistent identification elements (PIE) that have been tagged to the user’s browser. Although a user may remove HTTP cookies, ETags store the same information along with covert backup to reconstitute the data of deleted cookies.

      Most typically, ETags request Web resources on the condition that they have been updated since the user’s last visit to the site. For instance:

      A user may visit a site featuring a background that changes every week. On the first visit in a new week, the browser checks the cache and, finding no image or an outdated one, downloads the current background and caches it. If the user had already visited the site that week, the browser would receive the return response that the image had not changed. In that case, the browser would use the local copy in the cache, saving bandwidth and speeding load time.

      Unknown how this applies to my issues.

      More as I come across it….

    • #2470121

      Ooops. Last post awaitng moderation. Not sure why. I think I might have cut and pasted some links….

      Was on ETAG file questions and theme not being the culprit for me.

      bob99, do you have etag in windows/temp folder? This is new for me in the last week.


    • #2470137

      More Updates:


      52 tabs in Edge – very fast

      52 tabs in Waterfox Classic based on FF 61 – slow

      52 tabs in newly installed FF 89 Portable – could not use profile wholesale complaing opening ion an older version. Copied over bookmarks, etc and slow as mud.

      More to try / eliminate.


      • #2470188

        52 tabs in newly installed FF 89 Portable – could not use profile wholesale complaining opening ion an older version. Copied over bookmarks, etc and slow as mud.

        So “install” another instance of FF91.12 portable (install it in a directory where there’s NEVER been a FF installation either permanent or portable) and immediately have it open those very same 52 locations/sites. With all of those open, go into Settings/General and in the Startup section at the very top of that page, click the checkbox that says “Open previous windows and tabs” (if you haven’t already check-marked that box).

        Now, with all of those sites up and running within FF, close FF the way you normally would and wait a couple of moments. Now, open FF back up and see just how long it takes for all of those sites to come back up.

        By using FF 91.12, you’ll avoid the complaints you got from ff 89.

        I still feel that the reason that FF89 turned to mud when you copies some of those files and/or folders from your previous profile is that there’s a problem in that profile that’s now showing up due to the profile’s age and very heavy use over the years.

        If you can, make up a list of all of the 88 sites that come up when you normally open FF and save it to a plain text file. That will avoid there being any inadvertent formatting code within the text when you copy/paste it into a new browser session. Now, with all of those 88 sites open, do the same as before in the “newly installed” FF 91.12 portable, of closing it with all of them open and then reopening it after a few moments to see how long it takes them to be fully opened by FF.

        If they open very quickly (as fast as they used to or very nearly as fast), then the speed problem lies in your profile, and you need to build it back up from scratch with a FF refresh as I described above or by using the “Refresh Firefox…” button within about:support on your permanently installed copy of FF91.12 ESR.

        There’s another thing you can do for your settings in FF besides using a javascript file which may be making changes you aren’t told about. You can go to the Ghacks site and click on the listing for Firefox and once that page comes up, click on the listing on the right hand side of the page for “A comprehensive list of Firefox privacy and security settings”. That will get you to a list of many individual settings that you can enable on your own. That way, you know exactly what’s been changed and where within the browser. Since that article was written in 2015, it has been revised, but back in 2017. Due to this, there are some listings that won’t appear in FF because they’ve been built into the browser’s default programming (Mozilla has enhanced security in the browser over the last couple of years especially) or have become so obsolete they’ve been removed completely. Before each section and setting is a brief description of what each one does and any warnings about implementing some of them.

        In light of what I just said above in the last paragraph, I just remembered that there’s a thread about FF privacy and security here on AskWoody! It’s actually an AKB that was started by @Microfix a good while ago, but the settings in that thread are still pertinent today. That thread is where I found out about the mega-listing for FF settings on Ghacks. The location of the AKB is here:


        Carefully read through the posts in that thread (ALL of them, as there are good nuggets of info in each one of them) and then decide just which of the settings you’d like to implement.

        • #2470216

          Ahh, so much to reply to Bob.

          First, just been playing with all this all day. Headache. BOTH portables now crash after closing. Tried a myriad of things.

          As to 89 – it complained that the profile was trying to open an older version. This I have seen before. The profile knows it was at least modified with a newer FF.

          Again, I took a KNOWN Working Flawlessly profile from early July and it had the same speed issues. I do not think this is a profile issue. I am still betting ESET. Which is a whole nutha discussion.

          As to saving tabs to test with a new install – not even needed. If I import bookmarks, got to a folder with 40-50 bookmarks and click open all, it is virtually the same. That has been as slow. For me, another indication it is not profile.

          And last for now, every change I have made over time to the about: Files have had great resins and always worked. And since my 91.12 ESR installed was an update, all should be well managed. May not be the case for either portable. Should for the Portable 91. Not worried about the 102 as that is throwaway. Just there to see how the forced upgrade to this ESR in September will go. And I now know 🙂

          Must go rest. Truly burned out. Thanks for all your help and will read the other posts here and go out on the deck with a book 🙂

    • #2470120

      More curiousities from Martin Brinkman on ETAGS:

      Clearing the web browser cache should remove ETAgs.  Pants, who created the Ghacks user.js file, discovered some time ago that this was no longer the case in Firefox. She noticed that Firefox was not deleting ETAg data anymore when she cleared the cache of the browser, something that Firefox did before that time.

      She uses memory only caching on her system, and found out that disabling both caches (memory and disk) would defeat ETAgs but that it had other consequences at the same time.

      Still unclear if this could be part of the issue.

      bob99 – have you seen etag in windows/temp folder? New for me in the last week.

      Moderator edit: Bad image links removed.

      • #2470182

        bob99 – have you seen etag in windows/temp folder? New for me in the last week.

        No, I don’t seem to have those on either machine in the Windows/Temp folder. I do completely purge the browser’s cache (to include offline files) in every browser upon shutdown by default. This goes for all FF permanent as well as portable installations AND Edge as well.

        • #2470187

          Thanks. Not sure where ETAG is coming from. Is browser related. Could be a lot of things.

          And I clear caches as well. Does not seem to make a speed difference as I tested not clearing today.

          Still trying things. More and more frustrating.

    • #2470156


      Except my non-primary and original FF Profiles, the others were all ‘touched’ on the 1st of August, possibly by 3rd party disk-cleaning run. Compare with your own?

      My 91.x ESR can use the native ‘restore’ function.

      Check your “Enterprise Policies” switch. Also ‘Safe Mode’.

      • #2470161

        Thanks. Not the case for me and Safe Mode disables the ability to run sessions, so I disable all addons but and tried with no luck.

        • #2470207

          Not the case for me and Safe Mode disables the ability to run sessions, so I disable all addons but and tried with no luck.

          Please be as specific as you can, it should leave less room for any misunderstandings.

        • #2470210

          …so I disable all addons but and tried with no luck.

          ??? Not sure what you mean with the above quoted statement. 🤔

          Goes to what @satrow said right above this post.

          • #2470217

            Quick reply:

            Rather than safe mode, I disable ALL of my other addins except the session manager to test. And I also somewhere along this long DID try safe mode and opening tabs from bookmark folders rather than a session. Both of these had the same molasses.

            Back to morrow. Thanks again all.

            And I DO try to be specific when not burned out 🙂

    • #2470284

      OK, this is a “knock on wood” post.

      I’m about 2/3rds of the way back to working as I was. On my default 91 ESR installed.

      What did I do?

      1. I used SpeedyFox t compact my databases. After making a profile copy., of copurse. Just in case. But it has never created and issue.
      2. And the strange one: I disabled Fiemin which I have used every day for years and years. Ironicly, CPU usage dropped dramatically which I think was hampering the speed. However, RAM usage is outrageous and over 7GB for the Firefox processes.
      3. I want my cake and eat it , too!

      Nice having the loading speed back and much lower CPU usage. But the RAM might be an issue. Firemin released it when it got over 500 MB per process.

      And, this is newand roughly started when FF became groggy: These two new files in windows/temp every reboot: AdditonalThumbP{rints.xml and Etag. Cannot get enough info on them, where the =y come from and why. Nor do I know if they or what creates them are affecting Firefox at all.

      So off to see if a new version of Firemin. And tto play a little more. But feeling a little relieved at the moment.


    • #2470464

      So sorry about all the typos above written while I was excited 🙂

      OK, Firemin is gone. I am back to my 2-3 minutes 88 tab load. Very pleased. Still would like to know about those temp files.

      If I did not mention, I saw that my RAM was kept low managed by Firemin, but my CPU was pegging out at 100% usage and fan on fast and loud. Unusual. Cured by removing Firemin. I suspect that either Windows of=r Firefox more likely had an update and changed how they handle memory which caused this change around a week ago.

      But I mentioned that I thought Eset AV could still be the culprit and learned more since, so will start a new thread on my confusion and new learnings and ask for advice on ESET and HTTP scanning there.

      I’ll post a link here when I have that up.



    • #2470609

      My experience with Firefox is that it’s either a setting in about:config or an extension – about:config doers mot apply here so what I do is start FF normally and manually disable ALL the extensions – then try to see if the behavior still happens – if so, it’s not an extension and you can try a full uninstall and reinstall making sure to get a true fresh start – if the behavior is gone reactivate 2 or 3 extensions at a time to see which one is misbehaving. Hope this helps.

    • #2470725

      Caveat I am not using FF but Pale Moon things should be very similar.

      I would see if a recent addition to your tabs is slowing things down. Try putting about:performance in the address bar w/o loading your Tabs, then load the last session from Session Manager.

      Also about:profiles in the location bar will show profiles. The one labeled something like This is the profile in use and it cannot be deleted. would be the one you are using


      Just because you don't know where you are going doesn't mean any road will get you there.
      • #2470730

        Thanks. I think enough explanations above as to why it is not a tab – restored profile from 2 months ago when working, same opening sites from bookmarks menu, etc.

        Fremin was the largest culprit. Now working “acceptably”. Could be a little better hence tweaking what ESET AV might be adding to slow down such as HTTPS scanning.

        Getting there…

    • #2480416


      Posted this in the Firefox Updates topic:

      I updated today from 91 ESR to 102 ESR and major problems that have me beside myself.  Appreciate any help that anyone can offer. I feel like I have two flat tires and no spare.

      OK, all my 91 ESR’s updated today. I have an installed version as my default browser and a portable version on a thumb drive I can drag to the desktop.

      They run like mud. Worse. I used to have 4 Firefox processes running and now can have 30 or more. Uses 100% CPU most of the time. I used to fix that with this setting that is now gone:

      So that is likely at least part of the issues. The above solved a lot of that is all Firefoxes 91 and prior.

      Even when my tab groups open after a very long time, a third of the tabs were never fully loaded and need to be refreshed when I get to them.

      Its unusable. And since this is literally my lifeline to the world. I am beside myself.

      When I regain composure I will Google. I can’t be the only one. But something is very wrong. And it is not Firemin this time.

      Appreciate the help…


    • #2480512

      Thanks Alex. Trying to look at this more calmly since I live in my browser all day and this is painful.

      Number of processes depends on the number of open tabs. Was never this way before when set to Process Limit of . In FF 91 I would have ONLY 4 processes. Never more. Last night I hit between 42-60 firefox processes.

      As I have said before, I am a power user with FF. I have MANY extensions and addons – all which have worked for years which is not to say one of them is not the issue, but I doubt it. And I can open 20-25 tabs (I think – need to confirm) reasonably with less CPU stress, but my normal opening tab group has been as much as 122, which is not as high as it sounds compared to other users in perfomance threads areound the internet. And now with 88 tabs cannot open the group with total success no matter how long I wait.

      Need to have coffee and test some things. Back with any new news…


    • #2480514

      I have MANY extensions and addons

      Maybe here lies a problem.
      Try FF with no extensions/add-ons.

      • #2480572

        Thanks. Tried best I could. Cannot turn off all or cannot test the issue. So turned off most, used default theme, no change.

        Since last post learned:

        • Not likely extensions. I disable most and no change
        • Not a theme – default makes no change
        • Reinstalled a FFPortable 91 ESR on my desktop and not much better – so a site? This used to work as expected. So something in 102 changed something sytemically?
        • Lazy tab opening works but very slow. Could be my last resort. Testing more.
        • Had one tab “this page slowing Firefox” and fixed by deleting and rebuilding that pages cookies
        • There “could” be a previous change I made to about:config that is causing this. Only way to know is to RESET FF which means all extensions to be readded and configured one by one, Search Engines to be re-added, Download options to set, Toolbars to reset as I like them, etc. Not easy. maybe TRUE last resort.

        More as I discover it. Open to more ideas.


        And BTW, all these addons worked just fine with 91 ESR. So 102 somehow the culprit. And since 100% CPU until all tabs open that has to be a big clue.

    • #2480600

      And BTW, all these addons worked just fine with 91 ESR. So 102 somehow the culprit.

      You can’t blame a browser update for incompatible add-ons/extensions.

    • #2480622

      Why not? If they worked in previous browser version its possible the browser update now has an extension that is misfuncting and not yet uopdated. No?

      Anyway, making progress in several ways.

      Founf out that the reason portable versions on thumb drive always crashed on closing was errant su=yncing of bookmark backups. So that is solved. Not even sure I mentioned that as an issue.

      Lazy browsing may be the thing I have to do even though I never have in the past. Would love to know why now, biut suspect it is the lack of ability to change performance to 1. Is there an about:config to override that? Must Google.

      Other possibility is ESET NOD32 is slowing it down. Should be able to test that later this afternoon.

      Back with more.


    • #2480624

      Why not? If they worked in previous browser version its possible the browser update now has an extension that is misfuncting and not yet uopdated. No?

      Because extensions and add-on should dance to the browser’s tune and not vice versa.
      Browsers devs can change any feature disregard of any currently used extensions. Example: Google manifest v3.
      It is the task of extension developers to test their apps vs nightly, beta.. browsers versions. In FF example nightly: 107, beta: 106.

    • #2480733

      Well, in an ideal world, Alex. But many addon authors do not keep up and quite often nothing else as good out there to replace it with. I have many examples. So, yes, a browser update can break addons.

      Now, I had some promise finding that the missing setting from above was “supposed” to be in about:config at dom.ipc.processCount. Default set to 8 as previous versions, but alas when changed to 1 still opens dozens of FF processes. Right now for 60 tabs I have 57 ff processes running.

      There are a few related keys such as dom.ipc.processCount.webIsolated I changed from 4 to 1 with no change. I made sure the trues and falses that needed to be were set properly for this to work. It doesn’t. If it did I feel fairly confident it would solve my issues.

      So the only thing that seems to really help is lazy tab loading and that is so inconvenient. Adds a lot of time to my browser session. And that is now available from Tab Session Manager settings. I have not searched to see if it is an about:config setting. I will.

      Seems to be here:


      That also does not work. 🙁

      Tired. Time to take a break.

      • #2480958

        maybe don’t preload tabs


        Just because you don't know where you are going doesn't mean any road will get you there.
    • #2480736

      Hello Rebop2020, It appears you do know Firefox rather well so I am not going to give suggestions you already know or have tried.

      There are several people out there that are having troubles with Firefox 102 and above. Slowpoke had a freezing issue and finally got a new computer to fix it. https://www.askwoody.com/forums/topic/firefox-5/

      Others out there are still fighting a 2 month problem in the Mint forum and bug reports posted at Mozilla Bug Reporting.

      You should consider filing a Mozilla Bugzilla bug report with all this diagnosis you have been doing. https://bugzilla.mozilla.org/createaccount.cgi

      Make a bug report and get a number. They are developers and are supposed to investigate issues. Keep on them, don’t let them “ignore” you.

      Here are two bug reports currently being investigated for Firefox freezing issues.

      SW-WR/XFCE/Intel: Firefox window randomly freeze

      HW-WR/XFCE/Nvidia: WebRender occasionally goes crazy after suspend&resume

      I know yours is not freezing, but I want you to know there ARE issues after Firefox 102 was introduced. If you have a rather new computer, it seems most people are OK. However I have always commented, “Firefox appears to be made for new computer with 16 gigs of RAM.”

      I personally have moved over to Pale Moon about a year ago. I too am a user with many tabs open and Firefox was maxing out the RAM.

      I also noticed that yes, you are right, 91 ESR had a way to adjust the amount of processors you wanted to use and now in 102 ESR its gone (lack of user options is another reason I left Firefox). That would make another reason to post a bug with Mozilla is to ask, “how does one adjust that now?”

      Keep at it and good luck!

    • #2480746

      Thanks so much. Thoughtful post.

      You are supposed to be able to change the amount of processes at the above mentioned key in about:config. I would bet folding money that would fix my issues. But it does not work. A bug report is a great idea. Likely over coffee in the morning 🙂



    • #2480787

      OK, to make things workable for me requires changing a half dozen keys in about:config. Not a one of them does anything. Changing process count makes no difference in how many processes run. Changes to enable lazy tab loading does nothing. And on.

      BUT after what, 24 hours, I found a workable solution. Not the most elegant, but actually very functional:


      I should have been able to achieve this in about:config changes.

      And one more big bug.

      I could backup bookmarks from my desktop FF install, then restore on my portable version with no issue. Now when I restore to the posrtable, it chokes when closing trying to combine 2 bookmarks.html files before it fully closes and will crash. Every time. Broken.

      OK, some sleep 🙂


    • #2480961

      maybe don’t preload tabs

      Not understanding. Please explain.

      If you mean lazy loading, I mentioned that several times above and the option no longer exists in FF nor does the about:config key for it work.

      If you meant something else?

      • #2481987

        Likely that is what I was talking about, I am using PaleMoon so am still on an older iteration of FF


        Just because you don't know where you are going doesn't mean any road will get you there.
        1 user thanked author for this post.
    • #2481579

      Bookmarks backup fixed. Something (not me ) changed a key in about config causing a file to be created called bookmarks.html each time Firefox closed. Then the next time another file and the two would merge. It could crash if it closed before the merge completed. And no reason for this file. Baffled what changed the setting:


      Should be false.

      Getting processes down to manageable though not as good as in 91 required:

      fission. Autostart false

      Now I no longer get one process per tab opened.

      So, cannot find lazy loading, but major issues solved for another year 🙂

      1 user thanked author for this post.
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