shader is part of the intel graphics system. Try disabling the hardware acceleration in the settings and see if that changes things. Some drivers are just not compatible with some Thunderbird versions is about all I know. There is nt correct setting for given hardware for hardware acceleration so it is always a suck it and see answer.

Thanks for the suggestion. I've updated my driver and we'll see if that helps. I have to wonder what the heck does the graphics driver have to do with TB. At the time of the hang, TB isn't doing anything, as far as I can tell, that it would need to be so actively using it.

Version 140 fixes many performance issues. Including improved debugging of performance issues.

I don't know how I got so behind in updating. I'm now on 141.0.

With 'Check for Updates...' set didn't TB used to display a popup notification about a new update?

After updating drivers, Thunderbird and clearing the ShaderCache, the problem is still present. I have more Procmon data if anyone would be interested in look at it. Is there some resource that I can contact that can help me further? This is really getting under my skin.

Still trying to solve this. I'm considering that it may have something to do with retention policy on the folders. Is there a way to determine what folders have a non-account setting for retention? (other than opening Folder Properties for each folder.)

> I'm considering that it may have something to do with retention policy on the folders.

Why do you suspect this? What are your current symptoms?

Windows performance tools are not particularly helpful. Best if you do https://support.mozilla.org/en-US/kb/profiling-thunderbird-performance with the newest version of Thunderbird.

I have noticed that the folders where TB appears to be hanging while downloading messages are the ones where I've set a retention policy to not Use my settings account with Delete messages more than xx days old. xx is set to 31, 92 or 183 days. This occurs across several email accounts from several email services. I've never (I believe) seen it hang on a folder where the folder is set to Use my account settings. I'm using the Activity Monitor to see where the hang is occurring.

Oh, these are also folders where I have Filters sending messages. These filters are catching a fair number of message as expected, so actually it could be the Filter process that's hanging. Now that I think about it, that is also a possibility. Thanks for the poke.

Re: Windows tools: That is true, but those are the tools I some knowledge of to get an inkling of what the program was doing while hung using the CPU. Of course, I have no info on what TB was doing internally. Which led me down some rabbit holes. I'll take a look at what you've pointed to.

Thanks for the feedback. I understand the comfort and familiarity of Windows tools, but the aren't helpful enough to us. https://support.mozilla.org/en-US/kb/profiling-thunderbird-performance is more spot on. We can help you with it.

IIRC, retention policies fire every 5 minutes. But the actual time each folder fires will vary. So to simplify matters, can you reduce the # folders to just one or two before you do the profile?

Then start recording just before the retention process begins. Or, start the recording but keep Thunderbird otherwise idle until you know the retention has run.

Just to clarify. Am I trying to capture the hang or just the operation of the Retention Policy? The hang is very random, and does not occur for long periods of time (hours) and can be any of the folders with RP set. It is more likely to happen with all the retention set.

So, I expect a ton of data to sort though.

I'm a retired software engineer so I'm good with new tools and debugging software issues.

Thanks for clarifying.

I guess for starters, maybe just try to catch a slow period without any changes. If you need to capture with the profiler for a long period of time, like 10-20 minutes, you must tweak the sampling rate and buffer size. I have it all documented in the KB article.

It took a few days until I could get back to this. I have followed the instructions and captured a profile where Activity Monitor is displaying the message: Synchronizing: Comcast - [Email Id]. The message says: Bringing folder Bills up to date. Thunderbird has been in this state for over 10 hours. I captured about 2 minutes of this state. I am still able to use TB for other activities even when this message is present.

I have the Permalink. It looks like I have the profile uploaded. But where do I post the Permalink? The profile is named: Profile #134pfs. When I download and try to 'Load a profile from a file.' The profile opens in the browser but I don't see what to do after that.

Thank you for looking further into this.

You can post it here or visit https://support.mozilla.org/en-US/user/wsmwk/ and click "Private Message".

Please test version 142 as soon as possible.

I have installed the latest version. The issue is still occurring. I have captured with the profiler while Activity Monitor shows TB hung downloading messages. I can send that if you provide instructions. The file size is 11 MB.

I have looked at the wealth of data that the profiler captures. But of course, I can't interpret it very well. I have looked at the Error Console messages and see a number of errors. I imagine some can safely be ignored by a user. I can also send the log captured while TB was encounter the issue.

I have been observing the Error Console for awhile. I am seeing the following errors consistently around the time the hang happens:

17:32:07.937 RemoteSecuritySettings: failed to download CRLite filter ServerInfoError: Server 
 response is invalid TypeError: serverInfo.capabilities.attachments is undefined
    ServerInfoError resource://services-settings/Attachments.sys.mjs:40
    downloadAsBytes resource://services-settings/Attachments.sys.mjs:528
RemoteSecuritySettings.sys.mjs:659

This occurs 12 times in less than a tenth of a second. Is this error significant?