As of 7 September 2026. This guide is for desktop users and small IT teams whose Firefox stops responding on particular websites. Mozilla released Firefox 155.0.1 on 4 September. Its release notes identify a fix for pages combining CSS blur and backdrop filters (Bug 2068836). This offers a specific starting point for that symptom, not an explanation for every slow browser. Release notes
What is fixed, and what is not?
The notes also address a sidebar missing after restart when the option to hide tabs and the sidebar is enabled, plus profile and account display problems. A separate issue remains unresolved: certain SDR videos can look washed out on macOS (Bug 2068961). Mozilla says a fix will follow; 155.0.1 is not documented as that fix. Do not assume these desktop findings apply to Android, iOS or ESR. Mozilla
Requirements and the correct update route
You need Firefox to start, an internet connection and permission to use the intended update channel. Save your work, especially unsubmitted forms. On a company computer, follow IT policy rather than bypassing managed settings.
A desktop copy installed directly from Mozilla checks for updates in the About Firefox window. Microsoft Store installations update through the Store. For a Linux distribution package, use the distribution’s package manager; its package may arrive later. A lower version number on a different channel does not, on its own, prove a fix is missing. Update help
Step by step
- Record the starting point. Note the operating system, Firefox version, installation source and affected public page address. Describe what triggers the freeze: loading, scrolling or a particular action. Do not put private addresses or form contents in public bug reports.
- Check for updates. For Mozilla installations on Windows/Linux, open the menu and choose Help, then About Firefox; on macOS choose Firefox, then About Firefox. The check may start a download immediately. Use the intended updater for Store or distribution packages. Mozilla instructions
- Restart. Once the download finishes, use the offered button to restart Firefox. Check the displayed version again. In the Release channel, 155.0.1 contains the fix discussed here; if a newer version is offered, check its notes instead of forcing an older version.
- Compare the result. Open the same page and repeat the same action. Do scrolling, tabs and the menu respond again? Record the version and outcome. One successful attempt does not prove every freeze is fixed; repeat the original sequence.
- Narrow down a remaining freeze. Start a temporary diagnostic session using Help, then Troubleshoot Mode. Choose Open in the dialog, not Refresh Firefox. Test the same page. This mode temporarily disables extensions and hardware acceleration, among other features, so an improvement does not identify one particular extension. Afterwards, quit Firefox and start it normally. Diagnostic help
When should you stop and escalate?
If the problem persists, give IT or Mozilla support the exact version, operating system and reproducible steps. Remove sensitive information. Start with this reversible diagnosis: do not routinely delete profiles, disable protection or downgrade without investigation. Before deeper profile changes, make a backup; Mozilla explains how to copy profile data with Firefox closed. Such backups can contain sensitive information and need appropriate protection. Profile backup
Why updates are arriving more frequently
Mozilla switched to a two-week cycle with Firefox 155 on 1 September. Additional corrective releases remain possible. Our editorial recommendation for small IT teams is to schedule short recurring checks with a representative web application and record versions; do not change release channels without planning. Announcement dated 19 August
Transparency: A source-based guide, not an independently reproduced test or benchmark. No affiliate links or purchase recommendation. The specific macOS video issue remains unresolved at the source date above.