Is the process causing the disk activity Firefox? If so, I would open Firefox in Safe Mode, then close it to see if you have the same issue.

Are you using "Clear history when Firefox closes" to clear personal data when you close Firefox?

It is possible that some items like the disk cache extend the time it takes to close Firefox properly.

• Settings -> Privacy & Security
  Firefox will: "Use custom settings for history":
  [X] "Clear history when Firefox closes" -> Settings
• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

It is also possible that your security software interferes and causes issues.

You can also check the Processes tab in the Task Manager (Ctrl+Shift+ESC) to follow the progression of closing Firefox.

Thanks for your replies, which I really appreciate. I should have said I did try safe mode and separately disabling add-ins, all with no effect. However I hadn't thought of the cache, and that seems to have been the problem, so thanks again for your replies.

Firefox nightly and beta have multiple issues use firefox the original and you shouldn't have any issues use in settings for auto fill use your Google account for in app auto fill settings and set up options for open 8n app link with Firefox. Really you shouldn't have any problems with the firefox browser.

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