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Thunderbird 140.7.0esr (aarch64) on macOS26.02

For several days now, Thunderbird has been responding extremely slowly to mouse movements or clicks. This leads to undesirable results because emails are suddenly deleted that should not be deleted (due to forced double clicks). Or folders are not opened, or the wrong folders are opened.

The last change was updating Thunderbird. Is this a known bug?

I've been using Firefox for a while, and while there are many things I like about it, it has always been a resource hog. In the past I could get around this by just killing Firefox in Windows Resource Manager and restarting, but ever since getting a new computer an upgrading to Windows 11, it's gotten worse. Every couple of days my computer freezes for 10 or more minutes, I'm having to do a hard reboot ever few days, and I'm even bluescreening about twice a month. I'm pretty sure Firefox is the culprit because killing it will usually resolve the issue.

I'm wondering if there is some way to put Firefox in a sandbox so it does not consume nearly all available memory and other computer resources. It is by far the biggest consumer of resources on my system and I do not want to dedicate 4GB+ of memory to an app that is just showing a couple of web pages and playing YouTube videos.

I have been using thunderbird for a few years now on win 10. Just had to buy a new win 11 system and successfully installed it. transferred my emails, folders and contacts and all seemed to work fine. Now I notice that once I leave it for a few mins, it is unresponsive with just a blue circle where the curser should be. I close it and re open and all is fine again for a few mins. I have tried turning off my antivirus software and disconnecting from the internet but still the same fault. Any ideas please?

a black box appears over the search box when mouse is moved over the tab. Tried in safe and troubleshoot mode. Box still appears only in white I did find an answer previously but reinstalled firefox and the fix was lost. Problem resolved.

Thanks all for looking.

I was happily using TB 78.14.0 on Mac OS 10.9.5 and I switched to using TB 140.6 on Mac OS 12.7.4, and it's now unusably slow. I've tried: troubleshoot mode with add-ons off; compacting folders; removing and renewing msf files; emptying junk and trash. Is there anything else, or is this just a failure or incompatibility of the app? I can't see that there's any antivirus app that might be interfering. Can something go wrong when you export the files from one TB into another? I would be grateful for any suggestions. Tim

Just installed TB for Android on Samsung S24 Fe. Works fine but am unable to exit the application other than forcing phone back to home screen. Have installed on a Samsung tablet and the back button seems to be working OK. Anyone know of any issues with this phone and TB?

Imagine having more than 30 Accounts to be added on a single profile my concern is how will Thunderbird handles file size if it's using one file (MBOX) and if the file has no solution, can I create files and keep mails on them until they reach max size?

I have two installations of Thunderbird on two different computers 2 different locations, both are new installations. Both are on Windows 11. The one at home, works perfect, the one in my second home too except the unified toolbar is unresponsive, whatever I click there it doesn't respond, The X doesn't close the program, the - doesn't minimize anything, just nothing happens, any advise?

Comment, not a question. My now obsolete laptop ran Ubuntu 14 and its now 15 year old Thunderbird. Worked wonderfully well. My current laptop running Ubuntu 22 and Thunderbird 128.12.0 has driven me nuts since I got it. Slower than a snail loading. Confusing layout and function trying to group related messages into threads. I DO NOT LIKE IT.

I understand many of your customers might love the current Thunderbird for what they do with it. Can you somehow make available the older version of Thunderbird without all the fancy updates?

Thunderbird just updated to 144.0.1 (64-bit), and now I see a blank area where message list used to be. This true for all accounts and all folders.

I used to see this issue temporarily after compacting folders, but usually (but not always) went away and messages showed up. Sometimes I had to close and restart TB. Now even that wont bring up the lists. I'm dead in the water. And, yes, I did reboot my computer as well. Screenshot of this state attached.

Thanks for any help--it's urgent. Bert

Thunderbird performs a compaction. When it is finished the blue progress line is still showing on the bottom right hand side of the window.

You can select any folder and any view condition (read, all, tags etc) and no emails are shown anywhere.

• Restarting Thunderbird fixes the problem with no errors.
• This has happened a lot of times now and is consistent.
• If you force a compaction the problem does not occur.

Update: Usually, in frustration, I restart Thunderbird to fix the problem. This time, whilst typing this forum question, the problem resolved itself. I guess about ten minutes elapsed before the application righted itself. I will watch for the next incident and see what other information can be observed.

I can't add any email accounts in ThunderBird. The window keeps loading. Trying to uninstall and reinstall didn't help. It doesn't work on other devices either.

I tried to install the mailbox on another computer and the email configurator opened—I managed to add one account in this window, but when I tried to add another one, it didn't work like it does on other devices.

Downloading the latest version 143.0.

Have been having an issue for the past month or two where if left in the background firefox will slowly start to eat up my available ram. I was using it like this perfectly fine for years previous to now.

I dont have this issue when I'm actively using it, only when I tab away from it and specifically its not on screen. Once I tab back to firefox the ram usage immediately dips back down to normal. I have tried many things to try and solve this like doing a clean install of firefox, getting rid of extensions, clearing my browser cache, closing all other apps to verify it was just firefox, clearing my history, turning on hardware acceleration. Nothing seems to help, im really at a loss and I don't understand what changed besides it being updated in the past couple of months.

My computer is fairly heavy duty and I have 16gb of ddr4 ram that again was working perfectly fine to run firefox before these past couple of months. As a result of this issue however if left in the background for too long on accident firefox uses up all my idle ram and starts causing other programs to not be able to run and has even crashed my computer previously when trying to run a program like clip studio paint.

I have noticed that while running the firefox task manager there is definitely some difference in memory usage when i tab back in after letting it be in the background so I have attached screenshots of the regular usage while tabbed in and the captured usage when i tab back in.

Any possible solution is welcome because I really enjoy using firefox and i dont want to have to switch browsers unless absolutely necessary.

I am running TB. Using the Windows Performance Monitor, the usage jumps from 30% to 90% and then 100% once TB is open. I am running 1.128.14.0esr (64-bit). I have the before and after screenshots of the CPU, see attached. Is this known behaviour?

I tried the steps at https://support.mozilla.org/en-US/kb/profiling-thunderbird-performance to record. The Multiprocess Browser Toolbox window hung the 2nd time (the first time, nothing happened after Capture recording), then I left it 20 minutes and came back to the message that we were unable to connect to the browser within 30 seconds. It eventually finished, painful - htpps://share.firefox.dev/41tZ5xy