Thunderbird Community Forum

For a few days I'm having trouble with Asana mails (notification mails informing me about replies, comments, etc).

Clicking on the mail to view it freezes Thunderbird for a good 5 seconds while one CPU core spins at 100%. This only happens with Asana mails (or at least I haven't found any other problematic senders).

I guess it's a problem with validation or parsing of the mail's HTML content. But I don't know how to debug this.

I can't pinpoint exactly when it started happening, but it was around the time I've switched to the [new snap release track](https://support.mozilla.org/en-US/kb/channel-choices-thunderbird-snap-and-flatpak#w_snap-channel-changes-in-2026). But since this happens with Snap and Flatpak I think the culprit may be the 153.0 update.

Things I've tried:

• Clearing cache and msf files.
• Troubleshooting mode with add-ons disabled.
• Reinstallation. Creating new profile + importing old data.
• Switching from Snap to Flatpak
• Switching Message Body display to Plan Text or Simple HTML.
• Disabling HW acceleration.
• Checking console for suspicious output.

Anything I can do to create handle the problem or collect information for a proper bug report?

It's very odd. Normally moving an email, say from the Inbox to the relevant year's archive, takes "no time at all".

Which is true for all the mailboxes shown on the attached screenshot, EXCEPT for the four at the bottom. Moving even one message from Inbox to Yiddish can take ten seconds or longer (with the dreaded "Not Responding" occasionally). Moving something in the opposite direction is also screwy, only from those four.

I had thought that it was because they're rather large. This first started when there were just Yiddish and MSW, and I split off most of the earlier years into the archives shown. To no avail.

It's only an annoyance, but I'm puzzled about how such a thing could happen.

Also very slow tagging or untagging a message just in those mailboxes.

T-Bird is Freezing (Hang?) from start to freeze was 5 minutes and a few seconds. Have turned off hardware acceleration and now it freezes at just under 5 minutes. Have put on updates. Currently 153.0.1esr (64-bit). I have captured profile, and re-installed and picked up the profile. Still freezes. Turned off AV. Still freezes. I have compressed and "repaired" all folders. Still Freezes. I forced folders to get rid of anything older than 30 days. Still freezes.

I have been running the task manager, and T-Bird in frozen state is only using 4.3% of CPU at most. I do not see any slowdowns for any other program. So this is not a CPU constrained problem. And it certainly is not memory constrained.

All this started within the past month and I think it was after I put on an ESR update (don't remember which one).

I can kill T-Bird and start it and it will get mail if any, and will function for about 5 minutes and then freezes (or hangs). The system is set to fetch mail on start up and then every 27 minutes. I am not using Account hub (and don't know what it does).

One oddity -- This is a W11 Home system, and Mozilla keeps saying it is a W10 system. Could this be the problem? Wife is running a lesser laptop. It is also running T-Bird, but her O/S is a W11 Pro and she is not having this problem.

Thunderbird had been working great for both of us until after my wife stopped checking her emails for a couple of months. When she later opened the program her inbox started downloading hundreds of emails (very slowly) until her inbox contained well over a thousand. I started to delete the unwanted ones but it went very very slowly. I finally whittled it down to a few hundred but the program continues to run very slowly in all phases. In one instance, it took 11 minutes to delete 39 messages. Downloading and sending are not much different. I've done virus scans, checked settings, restarted the computer etc., all to no avail. And when we switch users, my Thunderbird email runs perfectly. I also contacted my internet provider (Spectrum) but they said it had to be a program issue. How can I restore my wife's email to normal function? Thanks, Joe S.

I have had Thunderbird from the time I acquired my Mac computer. This week it started to do something new. After a restart I opened Thunderbird. A box came up that says across the top System Integration. The cursor balloons, and hasn't stopped for the time I powered the computer, as least fifteen minutes. You know how the program icons are in a dock across the bottom. With other browsers open, hitting the Thunderbird icon doesn't bring its window into the forefront. This needs either a reset, or possibly a backup first. Is there a quicker way to fix this? Thanks in advance. I am not using a VPN; but I also have Thunderbird on my Windows 11. You might have seen a more recent thread on that installation. I included a screenshot. It was easier here to do that than on the Windows 11. On the Mac, I just had to use Activity Monitor to close out of Thunderbird in order to get its version.

Hello,

Every now and then Thunderbird pops up the notification in the screenshot. Can anyone tell me what it means and if I should do anything about it?

Alan.

hi :-)

My Thunderbird uses between 19 and 34 GB of RAM. It's cyclical (with a period of about 10 minutes).

What do you suggest?

Do I need to perform a performance diagnostic? https://support.mozilla.org/en-US/kb/profiling-thunderbird-performance

Do I need to follow all the steps listed on https://wiki.mozilla.org/Thunderbird:Testing:Memory_Usage_Problems#Diagnosis_Steps, or can I skip some of them?

Hi,

I'm running the latest version of Thunderbird 140.12.1esr on 15.7.7 (24G720) on an M1 processor.

I'm witnessing Memory leak > Thunderbird who usually use 800MB jumps to Gb up to 60Gb

It makes this version unusable.

Here is a loom of the incident: https://www.loom.com/share/0b8e661b42d64d749d80adfd71fd1e04

+ a screenshot

Anyone can help ?

Best Olivier

I am using Linux Mint Cinnamon 21.3 and Thunderbird POP3 email. I have 10 email accounts.

What I have noticed is the Thunderbird 128 series startup email check and/or "get all messages" is quite slow compared to previous versions.

Thunderbird 102.15.1 took only 4 seconds to check 10 email accounts, Thunderbird 115.18.0 took 5 seconds, but Thunderbird 128 and 136 series takes 15 seconds. All of these have used the same user profiles.

There is no antivirus software active. All messages are deleted from all accounts. No messages to download and checking for messages is still slow.

I have tried the Betterbird 128 series, a fork of Thunderbird, and it too behaves the same. Betterbird 115 series work fine, just like the Thunderbird 115 series.

Is this slowness in the 128 and 136 series by design?

what and who is meadow and why am i getting comcast mail sooner than thundershower it is just to slowit used to come up so much faster id get the new mail quicker now its so slow aand i do not want to uninstall and reinstall and lose my contacts and my extensions please if you know why so slow please let me know i know i sent one like this earlier but i though maybe gibving it time would be better but no it is not

If Thunderbird startup is stopped before tabs are loaded, they are lost. The tab fields at the top of the screen remain but they are empty. Evidently, tabs are stored only in a temporary location. This is a very annoying bug. Is there a way to recover them?

The Inbox on my Thunderbird emails shows 224 messages but do not open. I have tried opening and deleting but to no avail.

IMPORTANTLY I am still receiving new emails.

I realize this can be a macOS issue as the problem appeared when I upgraded to 26x but I'm hoping that maybe there's another way of allowing windows to be moved with a mouse. This issue appears only under tbird and not under any other Apple or non-Apple products.

The new child window(s) opens up in the default location(s).

The issue has survived several OS updates up to the current one. I switched from macOS 15x to 26x in around January 26.

Firefox does not really open any child windows that I could find but browsing windows work as expected.

Thunderbird causes my machine to 'hang' from time to time,

1. often for up to a second and usually a number of times in quick succession on each ocasion. Sometimes this happens frequently - say every 5 or 10 minutes - sometimes only after an hour or more since the past occurrance.

2. My machine hangs completely - nothing will work, mouse, keyboard, sound, other apps etc. If I happen to be typing (into any app - including Thunderbird - when this happens, input ceases, the cursor freezes and - if the problem persists for a second or two, Windows reports "[app] is not responding"

3. I cannot be certain, but I believe the problem occurs whilst messages are being retrieved.

This is a very serious problem as it means that I can never leave TB running as the problems it causes are not acceptable.

4. This means I cannot deal with incoming messages without periodically re-starting TB - which is an utter PIA.

I am running Win 11 Professional on a 2-year old machine with 64 Gb of memory. I have run TB in Troubleshoot mode, I have confirmed that the problem occurs regardless or whatever other apps are running (or none) and I have proven conclusively that no other app causes any kind of similar problem.

Looking forward yto hearing if others have had the same issue and what can be done about it.

When I log in to Thunderbird, performance is fine for a little while, and then suddenly and for no apparent reason it slows down so that it is unuseable (5-10 seconds to complete one click command). The task manager tells me that it is occupying c10% of CPU. After a while it stops being slow and I can work for another few minutes, and then it slows down again. It is unuseable. I am using Thunderbird 128.6esr (32 bit) with Windows 10.

All help gratefully received!

I am running ver 128.5.2 esr 64 bit on Windows 11. When I open Tbird, it takes at least 2 minutes to load messages. When i do as mass delete, it goes really slow also. I get a repetition of numerous mail titles across the top of the page when the messages are finally loaded, and they are old messages. How do I get rid of them? All of this has happened after the new version of Tbird was installed. Previously, everything I mentioned above was very fast.

At some point after one of the recent major updates, Thunderbird has become horribly slow. In particular, filters and searches. After typing the first character, the program becomes unresponsive for 6-10 seconds, and this continues this behavior after typing each character. At the same time, the screen will compress to the left, and then go back to normal size. The application becomes unresponsive, but there is no category in the performance monitor that is at 100% (CPU, RAM, SSD, Network, GPU). Thunderbird doesn't use more than about 20% of CPU capacity, and I have 24GB of RAM free, but still becomes unresponsive.

Do you have any suggestions?

My computer has NVME SSDs and 32GB of ram, so I don't think it should be a performance issue. I am running Windows 10 Pro.

Thanks

I just updated to the latest Thunderbird for Mac as of today (128.6.1esr) and unfortunately still have the same problem that first started with the last update: whenever I get a new email, I click on it, and it takes a full 6 or 7 seconds to display the email in the bottom preview pane. This used to be INSTANT and now it takes an extremely long period of time when you consider how many new emails a person gets overnight. The cursor actually beachballs literally every time.

Thunderbird does not do this on version 128.5.2esr - that version is quick and snappy no matter what I do.

I have no idea why, but TB is wonking out lately with strange errors?

The folder '[Gmail]/Sent Mail on me@mydomain.com' could not be compacted because writing to folder failed. Verify that you have enough disk space, and that you have write privileges to the file system, then try again.

I have a ton of space and have not changed anything on the PC?

Any ideas?