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Thunderbird has been running very slow recently - help!

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  • Nzaghachi ikpeazụ nke nickada

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For a few weeks Thunderbird has been very slow to start up, and sometimes seems to take several attempts.

Yesterday it started strangely, loading all of my emails in all accounts very slowly as if it was the first time it was loading them (from the beginning of time).

Today Thunderbird just seems to gradually get slower and slower after 5-10 or so minutes of running. Also yesterday it was extremely slow when I came back to my computer after an hour or two away.

I have even tried opening it in Thunderbird safe mode. That works for a bit but eventually the slowness returns. I just now updated Thunderbird so we will see if that helps, but I thought I should ask anyhow. (I use Windows 10).

Please help! Thanks!

For a few weeks Thunderbird has been very slow to start up, and sometimes seems to take several attempts. Yesterday it started strangely, loading all of my emails in all accounts very slowly as if it was the first time it was loading them (from the beginning of time). Today Thunderbird just seems to gradually get slower and slower after 5-10 or so minutes of running. Also yesterday it was extremely slow when I came back to my computer after an hour or two away. I have even tried opening it in Thunderbird safe mode. That works for a bit but eventually the slowness returns. I just now updated Thunderbird so we will see if that helps, but I thought I should ask anyhow. (I use Windows 10). Please help! Thanks!

All Replies (2)

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If you are using the Conversations add-on, disable or (better) uninstall it, as it can cause performances issue with Global Search since it is no longer compatible.

You should also check if the issue occurs in Thunderbird’s Safe Mode - there may be more add-ons that are outdated or no longer or not yet compatible with your current Thunderbird version.

If this does not apply, try this:

  1. Disable the Enable Global Search and Indexer option in Options > Advanced panel > General tab.
  2. Restart Thunderbird, then quit it again.
  3. Remove the global-messages-db.sqlite file in your Thunderbird profile (this is just for cleaning up).
  4. Start Thunderbird and see how it performs.

If you are not satisfied with the results, also disable Allow Windows Search to search messages in the same dialog and restart Thunderbird (this can cause performance issues in Windows 10).

If none of the above helps, there may be one or more folders that need their indexes to be rebuilt because there is some corruption, which can be done by right-clicking a mail folder > Properties > Repair folder. A "rude" way of doing this would be opening your Thunderbird profile folder, close Thunderbird and recursely remove all the *.msf files in that folder’s Mail or ImapMail sub folders. That however would take each folder to rebuild their indexes once when accessed (but only then), you would not know what folder index file was corrupted when interested, and you might lose some message flags or e.g. Watch Thread info.

There may also be some antivirus scanning involved, that you can (and some sources say should ) disable in the Options > Security panel > Antivirus tab. Additionally, such software may be the culprit and need an update, or you might be able to switch the email scanning off in there.

You can also open the Windows Resource Monitor and see what Thunderbird actually does, especially for reading/writing (and to what file(s)), perhaps even before trying any of the above.

Please report back if any of this helped.

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I have a new HP ZBook running Windows 10. I have not installed any antivirus software yet. I tried uninstalling and reinstalling Thunderbird.

It displays "Loading Message" and is running extremely slow. It is yunusable at this time.