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#1 2021-09-14 10:16:27

Condor
Member
Registered: 2017-12-01
Posts: 49

Thunderbird 91.1.0 feels sluggish / slow, high idle CPU usage

Some days ago, I upgraded to Thunderbird version 91.1.0. This new version “feels” sluggish, even slow in response to operating things in the UI. Htop shows considerable CPU usage (relatively speaking, I know that the absolute figures are not that meaningful).

A couple of examples:

  • The mouse cursor triggers mouse-over effects when pointing at e-mails or folders. The effect lags slightly when pointing at e-mails, htop shows CPU usage at 80 %. Pointing at folders, the mouse-over effect lags considerably, up to half a second/second with CPU usage at over 240 %. Before? No mouse-over effect, no lag ;-)

  • Dragging an e-mail or thread to drop it into a folder: Similar sluggish response as with the mouse-over effect. Before: No noticeable delay.

  • In the calendar, clicking the buttons for new event or new task produces the “sand clock” cursor, the entry window opens with noticeable delay. In contrast, the new e-mail window opens in an instant – closing it however produces massive delay: The pop-up dialogue window “Save this message to drafts …?” appears, but without buttons or content. They appear … after a looong while (didn’t time).

  • Even at idle, in the background, Thunderbird constantly uses CPU. (Firefox, as a relative, consumes some CPU frequently but drops back to zero in between.)

I know my descriptions are not hard data points. But as I use this application massively on a daily basis, those changes in responsiveness of the UI seem quite apparent to me.

No settings were changed in Thunderbird recently. I haven’t done anything additional for the upgrade 78 => 91 besides letting pacman do its work.


Does anyone else have comparable experience?

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#2 2021-09-14 11:37:51

Lone_Wolf
Member
From: Netherlands, Europe
Registered: 2005-10-04
Posts: 9,515

Re: Thunderbird 91.1.0 feels sluggish / slow, high idle CPU usage

Mouse-over :
hard to determine as many of my mails don't have a mouse-over at all. For those that do the first one has some delay.
None of my folders do show a mouse-over.

dragging : not noticed delays

calendar : don't use it, save draft message works normal

Idle cpu usage :
barely noticeable , but htop does show it. no idea if this was also the case with previous versions .

Overall thunderbird load on the system may be a bit higher then before .

What processor / memory / graphics / storage does your system use ?

Here are mine for reference : amd threadripper 1920x (12/24 cores) , 16 Gib, AMD RX580, 2x NVME2 ssd

Last edited by Lone_Wolf (2021-09-14 11:38:18)


Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.
Did you use the guided installer ? If yes, I can't help you.

(A works at time B)  && (time C > time B ) ≠  (A works at time C)

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#3 2021-09-15 10:19:03

A.J.Rouvoet
Member
From: Naaldwijk, The Netherlands
Registered: 2012-06-30
Posts: 37
Website

Re: Thunderbird 91.1.0 feels sluggish / slow, high idle CPU usage

Yes! And not just Thunderbird but also in Firefox I'm experiencing a very noticeable slow-down and increase in long CPU spikes.
I hadn't updated in a while, so it was a large upgrade for me and it is not so clear to me what changed where.

(I also found that Zoom has much higher CPU usage, but that could easily be coincidental.)

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#4 2021-09-16 20:01:52

Condor
Member
Registered: 2017-12-01
Posts: 49

Re: Thunderbird 91.1.0 feels sluggish / slow, high idle CPU usage

Thank you both for sharing your experience!

Lone_Wolf wrote:

Mouse-over :
hard to determine as many of my mails don't have a mouse-over at all. For those that do the first one has some delay.
None of my folders do show a mouse-over.

To clarify, the mouse-over effect does not show any details of the particular e-mail or folder. It is just a highlighting by changing the background color, nothing more.

Lone_Wolf wrote:

What processor / memory / graphics / storage does your system use ?

Intel Core i7-4790K (4/8 cores) / 16 GiB RAM / on-board GPU / two SATA-SSD (one for the root filesystem and swap, one for /home)

Not terribly new, I know, but should easily do this task…

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#5 2021-09-19 14:51:56

progandy
Member
Registered: 2012-05-17
Posts: 4,562

Re: Thunderbird 91.1.0 feels sluggish / slow, high idle CPU usage

Lone_Wolf wrote:

Idle cpu usage :
barely noticeable , but htop does show it. no idea if this was also the case with previous versions .

I delayed the update a bit, now I my Idle usage went from mostly 0% to 3-5% for thunderbird. (CPU: i7-8705G, during the test limited to about 50%, 2GHz; Unthrottled thunderbird averages <2% at idle).
Edit: Firefox uses a lower base (1-2%), but has frequenst spikes with something like 2 content processes each at 5-8%.

Fast mouse movements in the folder and message lists can run it up to 250% with the mouse-over effects, average active percentage without that is about 30%. I did not test that with the old version.

Last edited by progandy (2021-09-19 15:16:37)


| alias CUTF='LANG=en_XX.UTF-8@POSIX ' |

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#6 2021-09-23 12:28:13

post
Member
Registered: 2015-02-15
Posts: 28

Re: Thunderbird 91.1.0 feels sluggish / slow, high idle CPU usage

Hovering over folder pane results in high CPU load. There's a related bug report in bugzilla.

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#7 2021-10-11 13:45:23

Condor
Member
Registered: 2017-12-01
Posts: 49

Re: Thunderbird 91.1.0 feels sluggish / slow, high idle CPU usage

Thank you for referring to the bug report!

The workaround mentioned in comment #13 of the bug report fixes my issues and is worth trying if you experience similar issues.

I'll just copy it over for quick reference:

https://support.mozilla.org/en-US/quest … er-1435915

If I go to preferences --> config editor and search for the entries:

gfx.webrender.all
gfx.webrender.force-disabled

Switch the first one to false (it was already switched to false) and the second one to true (I switched this one manually) everything works smooths and no cpu usage jumps happen.

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