Why does Firefox's per-site process isolation (Fission) increase RAM usage exponentially on low-memory devices with 20+ tabs?

Background:** I'm a senior software engineer running Firefox Developer Edition on a Linux machine with 8GB RAM. I have Fission architecture (site isolation) enabled, … (자세히 살펴보기)

    • Background:**

I'm a senior software engineer running Firefox Developer Edition on a Linux machine with 8GB RAM. I have Fission architecture (site isolation) enabled, which I understand is now the default since Firefox 95+.

    • The problem:**

When I open 20 or more tabs across different domains, Firefox's memory consumption scales dramatically — often reaching 4–6GB of RAM for what should be lightweight browsing sessions. This is significantly higher than what I observed before Fission was enabled.

    • What I've already tried:**

- Disabled hardware acceleration → no significant improvement - Set browser.tabs.unloadOnLowMemory to true → partial relief

 but tabs reload constantly, disrupting workflow

- Reduced content.notify.interval → marginal improvement - Tested with all extensions disabled (safe mode) → RAM usage

 still high, confirming it's not extension-related

- Checked about:memory → large number of separate

 "Web Content" processes, one per origin as expected with Fission
    • What I'm trying to understand:**

1. Is there a way to set a maximum process count cap for Fission

  without fully disabling site isolation? I found 
  dom.ipc.processCount but changing it doesn't seem to affect 
  Fission's per-origin process spawning behavior.

2. Is browser.tabs.min-warm-process-count a relevant setting here

  and what is the safe range to modify it?

3. Does Firefox have a built-in memory pressure threshold where

  it automatically consolidates processes — similar to Chrome's 
  memory saver — and if so, which about:config keys control it?
    • Environment:**

- Firefox Developer Edition 151.0b10 - OS: Ubuntu 24.04 LTS - RAM: 8GB - Fission enabled: confirmed via about:support - Extensions: disabled for testing

Open

I cannot access the Chewy.com website on Firefox.

I can access Chewy with Safari, but not with Firefox. So the problem is not with my Mac settings and the problem is not with Chewy, the problem is with Firefox. Please … (자세히 살펴보기)

I can access Chewy with Safari, but not with Firefox. So the problem is not with my Mac settings and the problem is not with Chewy, the problem is with Firefox. Please address and fix it.

Open 15 1

why are my familiar websites suddenly asking for text or email verification?

Over the last week or so my personal websites (such as Banking, Amazon, Facebook, etc.) suddenly started asking for (text or email) verification to sign in successfully. … (자세히 살펴보기)

Over the last week or so my personal websites (such as Banking, Amazon, Facebook, etc.) suddenly started asking for (text or email) verification to sign in successfully. This only happens after a restart. (Sometimes I run a 'restart to untangle some glitch - but some Windows updates do a restart automatically.) And I have to go through all the verification stuff again! VERY ANNOYING!! Some MS tech this morning had me uncheck Cookies and other data in the Privacy and security category. But that didn't help. I just did a restart and AGAIN my bank(s) websites asked for a texted CODE. So did Facebook, and Amazon. Once I complete the CODE requirement it stays good until the next restart. And when I went to change that "cookies" option was nowhere to be found (to change it back) In SETTINGS>PRIVACY & SECURITY - NOW shows just the green button and box that says "STANDARD". I don't want or need this annoying added verification on every site that I use daily. I don't know exactly how or when this started...(maybe about a week ago).

Open

History listings doubling or even tripling up

I noticed that some sites are showing up twice in the history when you go to history and look at the sites you've most recently been to. At first I assumed it was happeni… (자세히 살펴보기)

I noticed that some sites are showing up twice in the history when you go to history and look at the sites you've most recently been to. At first I assumed it was happening just with Youtube, but I have noticed it with other sites as well. This started happening a day or so ago. I recently updated to version 150.0.3, and I have no idea why it's happening. At first I thought it might be because I was signed into sync, but this hadn't happened on previous versions of Firefox and I've been signed into Sync for almost a year now and never saw this occur in that time. I even tried signing out of sync to see if that fixed the issue. it did not. I vaguely remember something like this happening on a much older version of the browser, but I dunno if you guys ever had a fix for it or not. I'm including a screenshot of the phenomenon for the sake of visual reference.

Open

Fire fox app

Change my password word try to open from apple app keeps coming up. Down load was interrupted why. Also before I change my password word this was coming up as me 55npst… (자세히 살펴보기)

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Open

Can't log in to Firefox on my new Linux Mint. It's asking 2FA but I can't see it on authenicator

I Can't log in to my for Firefox on my new Linux Mint laptop. It's asking 2FA but I can't see it on my proton authenicator. My username and password are ok. Then the 2FA… (자세히 살펴보기)

I Can't log in to my for Firefox on my new Linux Mint laptop. It's asking 2FA but I can't see it on my proton authenicator. My username and password are ok. Then the 2FA box pops up asking me for the 2FA code. And I can't log in now to sync my Android Firefox with my Linux Mint Firefox. I recall setting up 2FA some years ago on Proton but don't recall ever using g it other than one. Can you please help?

Open 2

How to open a new container tab using keyboard shortcuts on Mac?

Before the update, I could use "cmd+shift+[number]" to open a new container tab. Now, nothing works. "cmd+t" opens a tab with "no container", which is completely differen… (자세히 살펴보기)

Before the update, I could use "cmd+shift+[number]" to open a new container tab. Now, nothing works. "cmd+t" opens a tab with "no container", which is completely different.

I already tried going to "about:keyboard", but opening a new container tab isn't even listed as an option.

Open 2

Delete "Weitere Lesezeichen" in sidebar

Hi, I searched the web for deleting the item "Weitere Lesezeichen" in the sidebar. I found only solutions for the firefox 85. In Firefox 85 should be a field for hiding t… (자세히 살펴보기)

Hi,

I searched the web for deleting the item "Weitere Lesezeichen" in the sidebar. I found only solutions for the firefox 85. In Firefox 85 should be a field for hiding this. Although in Firefox 150 it can`t be hided or deleted. I don`t need and I don`t want this "Weitere Lesezeichen". Any solutions?

Open

Строка над вкладками

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Open

Je n'ai lus accès à ma session d'hier

Bonjour, A l"allumage de mon ordinateur,ce matin, quand je clique sur l'icône "Firefox", une fenêtre sans mes onglets d'hier C'est une page m'invitant à télécharger Fire… (자세히 살펴보기)

Bonjour, A l"allumage de mon ordinateur,ce matin, quand je clique sur l'icône "Firefox", une fenêtre sans mes onglets d'hier C'est une page m'invitant à télécharger Firefox. Je n'ai plus accès à mon historique et, n'ayant plus accès à mes mots de passe, j'ai du mal à ouvrir mes sites préférés. Merci par avance de votre aide. Annie Le Drévo

Open

new versions

with the last and now the most recent Facebook versions i ahve beem having problems with Facebook, now it may be Facebook but i have it more on Firefox even with… (자세히 살펴보기)

with the last and now the most recent Facebook versions i ahve beem having problems with Facebook, now it may be Facebook but i have it more on Firefox even with extentions shut off i get i what is it please help

Open 4

How to sync two profiles separately for use on multiple devices without mixing up the data between the two profiles?

I have two profiles, one for work and one for my personal in the same account. I need to sync both of my profiles but do not want the information in the two profiles mix… (자세히 살펴보기)

I have two profiles, one for work and one for my personal in the same account. I need to sync both of my profiles but do not want the information in the two profiles mixed together. I need to sync the information as I have a desktop and a laptop that I use for work, and mobile devices and another laptop for personal matters. If I am on work travel and need to access my personal profile on my laptop (because schlepping two machines is silly!), I want to switch my profile to the personal one. then when I am done I want to switch back to the work profile. How can I do this and is firefox set up to do this?

Open

Unable to add icon bookmark to new tab page

Hi, Lately I haven't been able to add a bookmark icon on my 4-row new tab page. There's still to empty spots I would like to fill but can't find the usual + button. Thank… (자세히 살펴보기)

Hi, Lately I haven't been able to add a bookmark icon on my 4-row new tab page. There's still to empty spots I would like to fill but can't find the usual + button. Thanks for the help

Open

blink of white starting firefox 150.

since v150 came out ive been having an issue where i get a flash of white on start up if i have Homepage and new windows as Firefox home with a wallpaper... i have re-ins… (자세히 살펴보기)

since v150 came out ive been having an issue where i get a flash of white on start up if i have Homepage and new windows as Firefox home with a wallpaper... i have re-installed firefox and tested it as default and it still happens. seems the wallpapers have a delay till it displays properly.

Open 1

How to bypass SEC_ERROR_REUSED_ISSUER_AND_SERIAL error for local devices

I'm reposting a question already opened here because a moderator suggested to do so. Actually I though I was posting to the international forum from the URL... I was tryi… (자세히 살펴보기)

I'm reposting a question already opened here because a moderator suggested to do so. Actually I though I was posting to the international forum from the URL...

I was trying to access a local HTTPS website of an embedded device (a Siemens S7-1500 PLC) that is using a self-signed certificate, but was unable to go on (attached image #1, in Italian language) due to the the SEC_ERROR_REUSED_ISSUER_AND_SERIAL error. I've browsed a similar PLC webserver in the past, so the fact that the device exposes a similar certificate serial number is not so strange for me, considering also it's self-signed.

The problem is that I cannot follow the instructions of the Mozilla knowledgebase here because I'm not able to identify the correct certificate of the website!

In the attached image #2 you can see that the connection is detected as not encrypted, I suppose because only the form part of the HTML that is posting the data using HTTPS while the rest is using HTTP, but I'm not sure. If I click on the padlock icon (attached image #3) the info about the current certificate is not displayed.

Then I went into Tools > Options and searched for "certificates"; as you can see in the attached images #4 and #5, neither in the Servers tab nor in the Authorities tab I can find any item that is related to 192.168.10.2 (the webserver IP address) or Siemens (the embedded device manufacturer). But unfortunately the error persist! Initially there was a 192.168.10.2:443 line in the Servers tab and I removed it and restarted Firefox, but it didn't solve, so at the moment the situation is the one depicted by the attachments.

I had to use Microsoft Edge to access the website, but I would like to solve this issue and use Firefox instead. Is there anything else I can do to bypass the error? Why doesn't the error page provide a way to correctly identify the wrong certificate using its fingerprint and/or name? Or, maybe, is there a way to disable this check for local IP addresses or for items in a whitelist?

Thanks for your help.

Open 4

Snooze tabs not working after update, suggestions please?

Hi all, After the last update the former Mozilla Test Pilot "Snooze Tabs" isn't working for me any more, I tell a tab to snooze and it just stays where it is. https://add… (자세히 살펴보기)

Hi all,

After the last update the former Mozilla Test Pilot "Snooze Tabs" isn't working for me any more, I tell a tab to snooze and it just stays where it is. https://addons.mozilla.org/en-GB/firefox/addon/snoozetabs/

I've tried running with addons disabled and then running with addons active again and the behaviour is the same. It's the same behaviour whether I run from the toolbar or the context menu.

I'm presuming this problem is related to Firefox update mechanics. Any suggestions for how to get this working again please?

Cheers :)

Open 6 2

9gag website performance issue.

Hello brothers and sisters, i am need help! I'm experiencing performance issues when surfing the 9GAG website. The amount of RAM consumed by this page is growing exponent… (자세히 살펴보기)

Hello brothers and sisters, i am need help! I'm experiencing performance issues when surfing the 9GAG website. The amount of RAM consumed by this page is growing exponentially. It's gotten to the point where this tab can consume up to 5GB of memory, and that's not the limit. This issue hasn't happened before. I can't figure out what's causing it.

What I did to fix the problem: I reinstalled the browser. I reinstalled add-ons. I reset my old profile, saving only bookmarks and passwords. I reinstalled the operating system. None of this helped. However, my friends don't have this problem with this site. Please help.

Open 1