User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36 Edg/92.0.902.78

Steps to reproduce:

Every time I start Thunderbird 91.0.1 it launches very slowly (more than 30 seconds).
This started with Thunderbird 91.0.1. Before had no problems. Reinstall does not help. Calendar not in use. Have an inbox of less than 100 emails, but there are many subfolders in local files.

Actual results:

Every time I start Thunderbird 91.0.1 it launches very slowly (more than 30 seconds). This started with Thunderbird 91.0.1. Before had no problems.

Expected results:

Thunderbird should launch in few seconds as before (before version 90.0.1).

Thank you for the level of detail.

(In reply to Peter Stendahl-Juvonen from comment #0)

...
Thunderbird should launch in few seconds as before (before version 90.0.1).

What precisely was "before"? v91.0? v78?
Do you see an improvement by starting Windows in safe mode and then Thunderbird in troubleshoot mode?

• win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird

(In reply to Wayne Mery (:wsmwk) from comment #1)

Thank you for the level of detail.

(In reply to Peter Stendahl-Juvonen from comment #0)

...
Thunderbird should launch in few seconds as before (before version 90.0.1).

What precisely was "before"? v91.0? v78?
Do you see an improvement by starting Windows in safe mode and then Thunderbird in troubleshoot mode?

• win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird

What precisely was "before"? v91.0? v78?

v91.0 if memory serves. No trouble with that version. And before that v78 and at least that version started fast.

Do you see an improvement by starting Windows in safe mode and then Thunderbird in troubleshoot mode?

Yes an enormous improvement. That way Tb starts in about one second (1 sec).

With just troubleshoot mode, is it ok? If so, try disabling add-ons one after the other to see what is causing it.

Thanks for testing. That's a good result. Now...

Restart Windows normally, and start Thunderbird in troubleshoot mode.

1. If the bad behavior returns then the cause is some software or function that starts when Windows is started.
2. Otherwise, if the behavior is still good and problem returns after starting Thunderbird normal, then the cause is an add-on or some Thunderbird startup preference.

Please tell us the results.

(In reply to Wayne Mery (:wsmwk) from comment #4)

Thanks for testing. That's a good result. Now...

Restart Windows normally, and start Thunderbird in troubleshoot mode. If the bad behavior returns then the cause is some software or function that starts when Windows is started. Otherwise, if the behavior is still good and problem returns after starting Thunderbird normal, then the cause is an add-on or some Thunderbird startup preference. Please tell us the results.

Restarted Windows normally, and started Tb in troubleshoot mode. Bad behavior returned. The Tb start takes again more than 30 seconds.
Have disabled all Tb Add-ons, which does not help. (Used just on add-on; "Send later".) Have also disabled Kaspersky Anti-Virus protection, Comodo Firewall's HIPS, and WinPatrol totally. No help, Tb start still takes circa 37 seconds.

When launching Tb, the GUI opens almost immediately, but without the contents of Folders pane. It's the folders pane and Inbox view that take the 35+ seconds to be ready.

Will continue to disable some other programs in addition to those tested already (without success).

In the meantime, what next?

Should I tweak some Thunderbird startup preference?

(In reply to Peter Stendahl-Juvonen from comment #5)

Restarted Windows normally, and started Tb in troubleshoot mode. Bad behavior returned. The Tb start takes again more than 30 seconds.

It is pretty clear the cause is software or a function that starts when Windows is started. There is no need to look for a cause in Thunderbird.

Have disabled all Tb Add-ons, which does not help. (Used just on add-on; "Send later".) Have also disabled Kaspersky Anti-Virus protection, Comodo Firewall's HIPS, and WinPatrol totally. No help, Tb start still takes circa 37 seconds.

Disabling might be insufficient. Try uninstalling. I'd start with Kaspersky.

An alternative, which still might not work, start Windows normally with those programs enabled, and reinstall the Thunderbird program.

Pleased to inform that I am back to normal again concerning Thunderbird start times.

Before the issue was solved (will tell you later below how it was solved), I even acquired a license for Mailbird Business already. In addition to that I acquired a license for Thunderbird Migrator Wizard - Pro as well.

So for some time I had a slow starting (37 sec ready to go) Thunderbird v 90.0.2 mail client and a fast starting and opening Mailbird email client with same messages in both email clients. However, since I was not completely satisfied with the GUI of Mailbird (especially how it presents local folders), I tried to continue to solve the issue with Thunderbird, which I have used for more than 15 years.

I uninstalled Tb version 9.0.2. Then reinstalled Tb 78.0. Going backwards (downgrading SW) caused issues with application profile. Also Tb v 78 became unstable and slow starting.

Since I had a three days old (Acronis True Image 2021) back-up image of my system, I decided to do recovery of the disk. It took probably half an hour to recover the disk (image).

Thunderbird was hence recovered back to Tb v 9.0.1. That version of Tb started in ca four seconds (4 sec ready to go). I was very happy with that after all the issues I had previously experienced with Thunderbird 90.0.1 and 90.0.2 versions and program launch times.

Then updated Tb normally to version 90.0.2, and it started in ca four seconds (4 sec) as well.

I am very pleased with the outcome of the issue and how it was finally solved. Back-ups are valuable things.

Having invested personal work in Thunderbird deployment, use and evolution for more than 15 years makes Thunderbird a valuable investment for me. I am more than happy that I can keep Thunderbird. I like its GUI very much and am happy about the customizability of the awesome mail client as well. And now I am again very pleased with the performance of Tb. Tb performs again well considering there are little less than 4000 messages stored in hundreds of local folders. Inbox is only 110 messages. Sent messages is also very large. I have kept all sent messages there for the records.

Finally, thank you very much for helping me focusing in right area in trying to solve the unlucky issue. All is well when end is well.