Thunderbird unusable, very very slow and huge memory leakage.

Suggestions :

1) Set thunderbird to clear cache on shutdown Go to Settings, General, scroll down to Disk space and check "Clear Cache on Shutdown"

Restart Thunderbird to see if it helps

2) Shutdown Thunderbird . Once it's shutdown, delete file global-messages-db.sqlite. This file can be found in Thunderbird profile.

To determine where is your Thunderbird profile : click on Help and then Troubleshooting Information. Under Application Basic, you'll find Profile Folder ( the 8th element or 8th line ) and click on Open Folder ( right next to it ). Note the definition of your profile folder. Now you can shutdown thunderbird and then delete global-messages-db.sqlite and then retart it to see

Thank you for your very prompt response.

I found the "Clear cache on shut down" was already checked. The cache was 589KB, I don't know if that's bad.

I found the "Global Messages SQLITE" file and deleted it. It seemed to make no difference when I re-started TB. It was a 29MB file, is that too large?

Should I try a complete re-install, perhaps initially without the local Mail folder and then try adding message folders little by little to see if there's some corrupted folder?

Thanks once again for your reply.

Can you please verify if "Use hardware acceleration when available" is checked in Settings, if it is please uncheck it and restart Thunderbird to see.

Remarks : The 29 MB is not big at all. I don't think you should reinstall at this stage.

Thank you for your reply. I'm afraid the "Use Hardware acceleration when available" was not checked, but thanks for the idea.

Should I replace the "Global Messages SQLITE" file?

You already replaced Global Messages SQLLITE file ( by deleting it ) and it did not help, so I don't think you need to do it again.

I understood that you have excluded Profiles folder from Antivirus ( you mentioned in your post ), Would you mind shutdown Antivirus and restart Thunderbird to see ( only for a few minutes and restart Antivirus when you determine if it did help or not )

Would you be able to find out the size of Profiles folder ? You mentioned that Thunderbird at time uses a lot of memory : do you remember or can you find out how much ? and also what is your PC memory size ?

You mentioned that Thunderbird used to work fine for years and only recently it started to "act out" : would you be able to determine from which version of Thunderbird  ? ( you can find Thunderbird Updates history in Setting, General, Thunderbird Updates, and then click on Show Updates history

Does the problem occur in Windows safe mode?

In reply to Michel T, I tried EE Cyber Security (Norton) turning off Auto-Protect and Behavioral Protect. The security tool gave me several Red warnings, so presumably it did something. However, it made no difference when restarting TB.

According to File Explorer, the Profiles Folder was 978MB and contained 466 files in 40 folders.

Task Manager says TB was using 3.629GB of memory but this is continuously rising. The machine's total memory is 16GB.

Rick, Thank you for your interest, I've yet to try the Windows Safe Mode. I'll get on to that shortly.

Rick, I got the computer in to Safe Mode and TB was unable to reach btinternet mail.

However, according to Task Manager, it was still leaking memory at about the same rate as before and it was still largely locked up, e.g. I couldn't open any locally stored mail etc.. I've managed to get the machine back to normal mode and I'm currently working my mails through the Chrome browser.

Thank you for your interest and support.

Over 3G of memory for a small profile size is a lot according to my opinion ( I might be wrong ).

If you don't backup your profile regularly, I would suggest that you backup your profile before going further.

To backup Thunderbird profile : shutdown Thunderbird and then backup all files and subdirectories of the profile directory

Create 2 new profile lets call it PT01 and PT02 ( as for reference of this "conversation" ) ( https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-thunderbird-profiles#w_creating-a-profile )

Now start thunderbird using this new "empty" profile PT01, don't add any account to it. Go to Settings and look at different parameters ( for example go to General, up and down, ) in General, Appearance etc, go to help look at Troubleshooting information, and browse ....  : the purpose of this step is to see if Thunderbird is leaking memory ( without any account added ) and is it easy to use. Please verify memory usage during your "browsing" in Thunderbird settings .

Now start Thunderbird using new empty profile PT02. Now you add only 1 account ( if you have more than one ). I don't know if you using IMAP or POP, for this test purpose I would suggest to use IMAP ( because POP would downloads emails and delete some emails depending on your configuration to your PT02 ). The only thing you would do is this account is browsing different emails and at most send some "test emails". The purpose of this step is to see if this account would trigger memory leak. If there is no memory leak than add another account ( if you had more ).

Let try this and then we'll see if you agree.

Michel,

Thank you very much indeed for your reply. I'm sorry I've been a couple of days trying your suggestions and getting back to you. I did most of what you suggested, i.e. I made two separate copies of my Profiles folder and used the link you provided to set up two new "empty" profiles. However, I couldn't manage to get TB to open without an account, so I let it use my account at btinternet.

The extremely good news is that it it was stable and Task Manager reported only around 440MB of memory in use and hardly any CPU usage. There didn't seem to be any memory leakage. I was able to browse through the TB features in Settings and Account Settings. It felt like TB was working like it used to. Thank you so much; I feel this is making real progress!

Of course, there were no local folders. Do I now copy these back from the saved Profiles or is there some import process to be followed? Thanks once again.

Of course, there were no local folders. Do I now copy these back from the saved Profiles or is there some import process to be followed? Thanks once again.

In the file system, while Thunderbird is closed, you can copy the user-created files in Mail/Local Folders from one profile to another.

EDIT: Copy the user-created files that do not have a filename extension. You can also copy the user-created files that have an extension of .msf. If you do not copy the .msf files, Thunderbird will re-create them anyway. That can be desirable unless you mind waiting for Thunderbird to re-index many large files (if you have many large files).

Thank you very much indeed. ... I can't understand what might have caused the problem except that, in Mail -> Local Folders I did find a document file! I can't account for how it could have got there. Could that have caused an issue?

To find out you can move that document file out of your local folders and then restart Thunderbird using the original profile ( the one that triggers memory leakage ) and see how it behaves.