Can you start offline using

 -offline

and disable any calendars? Does that help?

Hi Wayne, Thanks for the tip of starting it offline. It looks like the calendar has nothing to do with it as when the calendar is enabled or disabled starting it offline shows no significant cpu usage. Even when I click the online toggle in bottom left hand corner, so it is online, there is no increment in cpu usage. Really odd. I have tried this a few times and it works, even when I manually 'get messages' the cpu stays under control. I put together a bat file on my desktop so I can run it easily in future. Anybody got any ideas what is causing this problem of thunderbird 7.2.2 becoming cpu hog when started online but runs normally when started offline and then switched to online?

I have a similar problem every morning when I open Thunderbird. Seems that whenever the Thunderbird team makes an 'improvement', they either slow down the performance or make some excellent add-ons obsolete.

Hi Duhnel, Commiserations. I think it is pretty universal that updates sometimes cause problems and when the product is free and is so good normally you cannot be too critical. A philosophical consideration you can afford when you are not in a rush to meet a deadline.

Have you tried the trick of starting in offline mode and then manually switching back to on-line? Day 2 of running 7.2.2 TB it is still the same behaviour with me that this makes the problem negligible.

I have a similar problem every morning when I open Thunderbird. Seems that whenever the Thunderbird team makes an 'improvement', they either slow down the performance or make some excellent add-ons obsolete.

Does your problem exactly mirror the new topic subject? (I just revised the title)

It is a very curious problem.

So you have absolutely no calendars?

Are you able to open tools > activity manager just after startup, and if so what do you see?

What happens if you disable checking for new mail on startup for half the accounts in account settings? (or all of the accounts if necessary)

Sorry this is so tedious.

Hi Wayne, I assumed you were asking me about calendars. I do have a works calendar and it makes no difference if the calendar is enabled or disabled. I just tried running the activity manager after I restarted with online mode and once again there was a lot of cpu usage. Please see the attached image which showed there was no activity and shows the cpu usage on the Windows Task manager. It is now a few minutes after starting Thunderbird and it is still taking up 18% of cpu but seems to be doing nothing. Patrick

HI Wayne, I disabled all the accounts for message collection on startup and normal checks etc. Just deactivated all the boxes in server settings related to messages. Started up Thunderbird and the cpu usage is worse, it is up to 25% and takes forever to move up and down the accounts pane with the scroll bar. Strange. One thing, that might be worth mentioning, is that I do have a lot of local folders, along with subfolders, setup into which I sort my emails and there are a lot of them which have built up over the years. Is there some sort of index build that takes place on the new Thunderbird which might be the cause for the thrashing taking place?

Regards Patrick

Hi Wayne, I can add also that occasionally TB goes in to CPU hog mode intermittently through the day. It seems if you take it offline and online again then this curtails the high cpu usage for a while.

I have started the process of disabling the accounts one at a time to see if that makes a difference. I have started with my yahoo account which the other day, upon recommendation from Yahoo, I changed the password as it was complaining that TB was not a secure application (Cheek). regards Patrick

Patrick, thank you for continuing the investigation.

Which antivirus SW do you use? Can you capture a short profile during one of the high CPU periods, using instructions https://github.com/thunderbird-conversations/thunderbird-conversations/wiki/Profiling-Conversation's-Performance

Thunderbird 78.2.2 is very slow in going from one folder to another--from one inbox to another, from inbox to sent, or inbox to spam. This does NOT appear to have anything to do with how long the program is open. I noticed this immediately after an upgrade.

Hi Wayne, Sorry for the delay in getting back to you, I was out of the office for a couple of days. I am using Windows Defender as Anti-Virus.

I have a shared profiles on https://share.firefox.dev/3cmkvSg

I launched the process and it went into CPU hog mode. I navigated to the performance recording facility and starting recording. It did reach 100% buffer usage pretty quickly and did start cycling round.

Thunderbird continued to hog the cpu well after the performance recording stopped.

Downgraded to 78.1.1. Performance problems went away.

Hi rmrubin, Thanks for the tip on 78.1.1. I will downgrade once I am satisfied Wayne does not need any more diagnostic info. Regards Patrick

78.3.0 is just out. you might give it a try.

Hi Wayne, Thanks. I will as it is getting tedious have to stop and restart. I will let you know how I get on. Regards Patrick

I upgraded to 78.3.2 and still have this problem. Just watched Task Manager and Thunderbird peaked at 32% of CPU during startup! Tried to startup offline and it ONLY went to 29.9% CPU. There is definitely something amiss in this upgraded.

Hi abird5806, Yes I checked today and my Thunderbird is also on 78.3.2 and still suffering from the same issue. Could you confirm whether you are on 32 or 64 bit version? I am on 32bit and was wondering if it was worth the trying to switch to 64. Thanks Regards Patrick

By the way I do still get the benefit of no performance issue on starting in offline mode. However it will eventually at some point degrade in performance but the restart in offline does defer enough for the software to be usable for long enough to get the essential work done.

There's definitely something wrong with Thunderbird 78. I've noticed a severe regression in performance. Things that were fast are now slow. I didn't have this problem with previous Thunderbird versions.

I'm running Thunderbird 78.3.2 (64-bit), but hopefully not for long: I need to find a downgrade to a previous version, and try that. It was much faster then. It's definitely not a problem with my computer, everything else is still fast, except for Thunderbird.

Anybody else having this problem, and noticing it start with Thunderbird 78?