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Lately, when I try to click on a different mailbox or message , nothing happens. repeating clicks sometimes works, and sometimes i have to first click on what I was previous viewing to get what I want to highlight, or click on different areas of a message or mailbox to get it to work. I am on mac tahoe 26.2. Did not have this problem before. What can I do to fix this problem?

Thanks Dan

Thunderbird has become crazy slow. 5-10 minutes to display an email. It's not my email server because my phone connects to and displays email fast. I have been through all the advice that I can find and cleared, checked, disabled everything that might slow it down. Still crazy slow. If I kill it and restart, I get about 3-4 minutes of reasonable performance and then it just stops. Latest Release Version V147.0.1.

i have a fast machine with 32Gb memory only 60% used, everything else runs fast

I don't want to junk Thunderbird, but it's unusable.

Help!

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 posted this question some time back but didn't receive any helpful answers and don't know where my post is. In the upper right-hand corner there is suppose to be 3 symbols. One to lower the app, one to make the app full screen or partial and one with an X. I have jumbled symbols where the 3 good ones are. It does it in trouble shoot mode. I tried disabling addons but I can't get the normal symbols back. Here's what it looks like... Thank you for any help.

Hey there since a week when I brows with Firefox on Windows desktop the RAM uses jumped from around 60% spiked to 92-95% RAM and that changed just come a long a week ago. If change brows like Chrome different story, back down at 65. So you can also see a massive number on Firefox system running.

Question: Whats the reason for the change? What happend?

Best, Janosch

Some websites won't load at all while other are very slow to load but some will load just fine, example Crunchyroll (screenshot attached) won't load at all its just spinning loading icon and a white page but if I try it in a different browser it works just fine, but with Youtube it will load but is choppy and low quality videos and same thing as before I load it in a different browser and no problems. I have tried every possible solution I can find from clearing cookies and cache to refreshing Firefox even scanned for malware and virus nothing has worked please help me figure out what is happening and why it's only with Firefox that I am having this problem and its not hardware can play online just fine and download games from steam perfectly fine.

For some time now, TB (147.0.1 (64-bit)) has been VERY slow loading, the first thing in the morning. If I close it and re-open, it opens at the normal--and desirable!--speed. Any thoughts? Regards, Dave

I've been using TB for years. Lately I can be browsing the Inbox when the contents will disappear and I get a message saying something like no messages found. After about 30 seconds the Inbox is displayed again.

TB never used to do this and it is similar to Firefox refreshing the screen which it also never used to do this.

Also how do I get from the Beta version to the standard version?

1. I've drafted an email, then hit save / closed the email and opted to "save changes". 2. I try to edit that email, but it is just "flashing" in the preview screen. I right click on it to "edit draft message", but that just brings up a blank email. 3. The status in the bottom left of the screen shows "loading message..." "downloading message", repeatedly. 4. It was working fine earlier in the week, but Thunderbird Desktop Version 140.7.0esr | Released January 13, 2026, seems to be when the problem started?

Whenever I start Thunderbird, I get messages such as that some mailboxes cannot be compacted and some filtering cannot be done "because another operation is in progress". Why is this? How can I prevent it? It is a nuisance having to go and chase down and correct the filtering that has not taken place.

I have the following very frustrating symptoms:

1) Thunderbird will frequently decide that it does not have the headers for a particular folder, and will reload them. This is in spite of the fact that I had all the headers the last time that I used the program, and I have not restarted Thunderbird or the computer (although I may have put it to sleep). In one specific case, I clicked on my Inbox, and TB started a "compact" operation, and then it started to download *all* of the headers. Eventually it produced an error message for the compaction: " The folder ‘Inbox on williamatwood41@gmail.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."

2) Thunderbird will often state that a summary file cannot be opened: "Unable to open the summary file for Drafts on william.atwood@concordia.ca. Perhaps there was an error on disk, or the full path is too long." I have seen this for the Drafts folder, for the Inbox folder, for the Sent folder, and for arbitrary folders that I had previously opened successfully.

3) One day, I clicked on a folder that contained 6116 messages. I saw it download all of the headers. Then the right panel declared "No message found."

The next day, I clicked on the same folder. While downloading the headers, TB listed the low-numbered messages on the right side (upper panel), and then switched to the most recent message once all the headers had been downloaded. So, the behavior changed from one day to the next.

All of this seems to have started when I placed a restriction on the length of time that messages are synchronized. This was done because I was running out of disk space on my 250 GB disk. I subsequently replaced this disk with a 500 GB disk, but have not (yet) relaxed the constraint, because I wanted to get to the bottom of the problem.

My best guess is that setting the disk space limit has triggered some misuse of a pointer, which is resulting in the garbage-in, garbage-out syndrome. However, I could be way off.

I would be very happy to work with anyone on the TB team, and invoke whatever debugging tools are necessary (under direction) to find the root cause of this error.

What minimum memory spec is recommended for current Firefox usage? Have new computer with 16GB memory, 512 storage, intel core Ultra 5-225 processor & windows 11. Have not set it up yet.

When creating a new email and entering a recipient address, Thunderbird automatically suggests addresses after typing a few characters. However, in my case the auto-complete suggestions take about 10 seconds to appear after I start typing.

I am using Thunderbird version 149.0.1. My settings under Settings → Composition → Addressing are as follows:

☑ Local Address Books ☐ LDAP Server ☑ Automatically add outgoing recipients to: Collected Addresses Initial Directory for Address Book: Last Used Directory

I would like to understand what kind of search Thunderbird performs when auto-completing email addresses.

Also, if anyone has experienced the same issue, how did you resolve it?

Any insights or advice would be greatly appreciated.

After an automatic update of my windows 11, the thunderbird has real perfomance problems! the program open very slow, it freeces permanently, that the program is not usable anymore. I have deleted Thunderbird and reinstalled but it still has the bad performance. Thunderbird on my Laptop with windows10 performance without a problem, is fast and does what it was designed for! What can I do??????????????

Hi,

When switching from FF 128esr to 140esr our customers noticed a massive impact in performance for certain webapplications. All Applications effected heavily use pdf-files, users are working mostly exclusive in firefox. Performance is ok when the day starts but gets bad fast. Sooner or later working is no longer possible and firefox needs to be restarted.

The users work on Citrix Desktops, but difference in performance is also seen in Firefox localy (not as bad but its there). Cross-tests with another browser are not possible, because the application works only in FF.

We tried removing almost all policies effective to rule out a specific hardening setting We tried every setting we could find linked to cache (as it seemed related to that) but without success. We collected logs with the Firefox-internal Tools but could not identify a specific Problem.

Any Help is apreciated, thx in advance

Well, I just updated and still have the same problems. This browser is simply impossible to use; I can't even throw it away and forget about it: it can't load a single page without getting stuck halfway through, after which the app freezes and has to be interrupted, unloaded from memory, and only then (maybe) will the page load! It's been like this for six months now. It's probably time to ditch it completely!

It is my custom to run spell check after typing an email. Today, sudenly, the write window hangs when I click on spelling. Does not happen in troubleshoot mode. I have no extensions installed and default theme. I did try disabling hardware acceleraton, but did not help.

Yesterday all workd OK, and thre have been no changes to the computer snce.