Firefox Community Forum

Hi everyone,

I run a construction estimating website where we share project-based cost estimates and detailed breakdown for contractors, architects

I’ve noticed a weird issue in Firefox lately.

Some of the heavier pages (especially ones with large tables, detailed breakdowns, and embedded content) start getting really slow or sometimes even become unresponsive in Firefox. The same pages load completely fine and smooth in Chrome, so I’m trying to understand what Firefox might be struggling with specifically.

I already tried the basic stuff like clearing cache, testing in private mode, and disabling extensions, but the issue still keeps coming back.

It seems more noticeable on pages with a lot of structured data and embedded elements, so I’m wondering if it could be a rendering, memory, or layout issue on Firefox’s side.

Has anyone dealt with similar performance issues on Firefox with data-heavy or content-heavy web pages?

What should I look into next: layout structure, CSS rendering, JS execution, or something Firefox-specific I might be missing?

Any guidance or debugging tips would be really appreciated!!

Greetings and Good evening Due to restoration of windows Mozila was uninstalled on 03/06/2026 It had all history and data since 2021 Please help me to restore this. Please tell me how this can be done? Thank you Regards Himanshu Kotecha Account id [edited] gmail.com

I've uninstalled Firefox and reinstalled it and cleared the cache. And it's still either not linking to certain sites at all or not, opening them correctly or completely. I don't wanna spend any more time than necessary on this since i've tried various ways to fix the issue.. If you can help me, that would be great. I guess I could use chrome, but I have used firefox for years.And as a rule, haven't had any problems up until now.

I am having problems with logging into the VPN app. I paid a one year renewal in November 2025 and have had access to the app for both logins that use this computer. It is an Apple M1 Macbook Air. On Wednesday, when I tried to connect, it sent me to a page to select a plan for payment.

https://www.mozilla.org/en-US/products/vpn/?utm_medium=vpn-client&utm_source=desktop-signup-flow&device_id=602c31e5c3e043c687df2d1e7fc17da1&flow_begin_time=1779492973967&flow_id=8baedf7abe0402e07ee2f21622b22c13e6f85621900a55935f3e1a2455c42d0c#pricing

Then when I tried to sign in again, it gave me the spinning circle shown in the attachment. It has now been a couple of days where I have not been able to use the app.

I do have access to the built-in VPN for one of my logins, but not for the other one. I have gotten replies from general support that told me to try the special support for VPN.

Barry

the top bar in the browser is so small it is hard to read and i find it difficult to access the icons. increasing the value of "layout.css.devPixelsPerPx" increased the browser text but did not affect the top bar. Is their another approach or is their a magnifier the will work. Thanks.

I tried using the private window option on Firefox to log into Walmart.com, and I was able to log in. This is a work around, but would still like to know what's causing this issue.

According to my settings, Firefox should clear the cache completely. Bur it is never fully cleared, there are always about. 9.3 MB left at the temporary data. It should be 0 MB. Even clearing the cache "manually" does not clear it completely. HOW CAN I CLEAR MY CACHE COMPLETELY? (Firefox / Windows 11)

See two attached Screenshots

Suspected sessionstore.jsonlz4 corruption possible Sync rollback conflicts -

Please direct post to Sumo forum including jscher2000 or like-minded wizards.  Chat takes you down a never-ending rabbit hole.   Sync rollback conflicts - extremely large tab sessions spontaneous restoration of previously closed tabs during live browsing

Read several different instructions on Chatgpt that takes you down a never-ending rabbit hole. Firefox is restoring previously closed tabs from days or weeks earlier without user input during active use while typing in the middle of the keyboard with an activated red stylus mouse - used frequently and/or with an external mouse. The thumb pad is turned off. There are no shift, windows, 7 strokes. Upon restart of the computer, the Firefox settings are set to restore only active tabs open from previous session. This is a Lenovo T16 Thinkpad product no. 21HH003yus. The issue appears to be related to session restore corruption, possibly triggered by very large tab volumes (hundreds of tabs). Windows 11 that tabs reopen during active typing (not startup) hundreds of tabs open whether Firefox Sync is enabled ???? whether crashes/freezes occur - no whether the same old tabs repeatedly resurrect - no, but there are so many of them from weeks and months ago. whether you use session/tab extensions  ??? Believe recent version of Firefox or close.

Help please direct post to Sumo forum including jscher2000 or like-minded wizards familiar with suspected sessionstore.jsonlz4 corruption issues. Thanks so much!