[Bug]: Opening and closing tabs causes long browser freezes.

[VirtualShaman]

Pre-Submission Checklist

• [X] I have checked the existing/closed issues to ensure this issue has not already been reported.
• [X] I am using the latest supported version of the browser.
• [X] I have tried disabling all browser extensions/add-ons to rule out interference from these.
• [X] I have tried clearing the browser cache and cookies.
• [X] I have checked with a new profile and the issue still occurs.
• [X] I have provided detailed step-by-step instructions on how to reproduce the issue.
• [X] I have included relevant screenshots or console outputs.
• [X] I have checked that this problem is not occurring in the latest version of Firefox ESR.
• [X] This issue is specific to this browser and does not occur in other browsers.

Bug Summary

Every day sometime after the middle of my work day every day the browser will get dramatically slow to the point of feeling frozen and it gets slower the longer I use it. Closing and reopening fixes the issue but the tabs on my second window are dropped and it takes time for the browser to fully close and reopen

I am using the Flatpak version on the latest LTS of Ubuntu (22 then updated to 24). I also have tab unloading enabled to prevent too many tabs from slowing down the browser.

Reproduction Steps

1. Use the browser for multiple hours
2. Profit

Expected Behavior

The browser to be just as fast in the afternoon as it is in the morning

Actual Behavior

See Summary

Screenshots

https://github.com/user-attachments/assets/8f000183-9981-43fc-a768-e387bddbd46b

Browser Version

Flatpak 11.18.1.1

Operating System

Ubuntu LTS 22 & 24.04.1

Additional Context

No response