topic Re: Thunderbird is extremely slow after the new UI update 115.4.2 in Discussions

Thunderbird is extremely slow after the new UI update 115.4.2

DontWantAccount — Sun, 12 Nov 2023 10:54:57 GMT

I've got this big new update with new UI that simply doesn't work.

I do lot of operations over IMAP and the UI rendering is so extremely slow, that I'm unable to work with my mailboxes. Steps to reproduce, using IMAP, with config to mark as deleted and manual purge:

* Select 500 unread email messages.

* Delete them

* Purge the mailbox

It either takes very long, while rendering each message change back and fort, or completely freezes.

How do I downgrade and block further autoupdates?

Re: Thunderbird is extremely slow after the new UI update 115.4.2

JTijssen — Mon, 13 Nov 2023 15:19:56 GMT

As a fanatic Thunderbird user for many years -for that reasson made a free dontation- I am very disapointed and have the exactly same problem. Please solve this. Otherwise, I like to downgrade too....as soon as possible..... as it is unworkable at this moment. My mails are my business life line.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

Angeles — Wed, 15 Nov 2023 09:49:01 GMT

I have the same problem. Changing the user interface does not bring any advantage, it forces you to start a new learning curve (adaptation). If it also creates stability problems, it means that time has been wasted on the superfluous instead of improving the productive. Anyway, thank you for making this wonderful working tool available to people.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

endedasende — Wed, 15 Nov 2023 17:35:19 GMT

Same slowness when deleting similiar amount of messages, using POP here, so this is just UI i guess.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

droogiee — Thu, 16 Nov 2023 01:04:14 GMT

SAME!!! driving me NUTS on all 8 of my different machines i use!! super slow!! hate it!

Re: Thunderbird is extremely slow after the new UI update 115.4.2

skurarebapi — Thu, 16 Nov 2023 16:53:28 GMT

nice

Re: Thunderbird is extremely slow after the new UI update 115.4.2

Anonymous — Tue, 05 Dec 2023 18:50:33 GMT

Thunderbird on Ubuntu 20.04 LTS. Extremely slow after upgrade to 115 (currently 115.05.0 (64bit). I am using Thunderbird for over 15 years and it was never bad like now. Really fed up now., it has been lagging since some time in September. Multiple sequential upgrades never fixed anything. Thinking to switch over to something else or downgrade. It seems that mozilla team shows more and more ignorance to public

Re: Thunderbird is extremely slow after the new UI update 115.4.2

DontWantAccount — Tue, 05 Dec 2023 20:45:56 GMT

I ended up downgrading, and losing all my settings in the process. Version 102.15.1 seems to be usable.

I went to https://www.thunderbird.net/, copied the link from Download button and replaced the version.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

Anonymous — Tue, 05 Dec 2023 20:56:15 GMT

I am also running 115.5.0 (64 bit) on Ubuntu 18.04.6 LTS and it runs a way much faster, basically acceptable. The same accounts, same settings. In fact it includes much more historical data on disk, which does not affect performance at all.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

KingDeB — Sat, 09 Dec 2023 16:29:17 GMT

One account works fine and the other one is so slow I age a year every time I try to delete a message.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

1di9 — Mon, 11 Dec 2023 13:36:04 GMT

Exactly same problem with Thunderbird in Supernova version (expecially in latest release), slowliness everywere.....and not in selecting and deleting or moving tons of email, but simply openig emails just received...

I'm a Thunderbird user since first release and every time I can I try to recommend it as "the best mail client", but with those slowness problems I only risk making a look bad.......I'm very disappointed

Re: Thunderbird is extremely slow after the new UI update 115.4.2

Misterjat — Thu, 14 Dec 2023 13:16:49 GMT

Like so many others I find the current version (115.5.2) SO SLOW. Simple deleting just ONE email can take at least 10 seconds and as the screen doesn't change you cant be sure that the <delete> command has registered. It is VERY frustrating to say the least.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

nick_theboatman — Mon, 18 Dec 2023 01:05:13 GMT

I appear to have an auto-update that went in yesterday without me noticing.. now 115.5.0 64 bit on Ubuntu 22.04. TB just ground to a halt. I don't know what is happening but this has just become unusable. If it is re-indexing then it is re-indexing the _world_.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

Andrax — Mon, 25 Dec 2023 16:43:27 GMT

Thunderbird freezes.

I need to install last year's version and cancel updates.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

nick_theboatman — Wed, 27 Dec 2023 22:58:46 GMT

(and to add insult to injury:)
9. click "help" tab / "about": 9 seconds to display the pop-up ...

Re: Thunderbird is extremely slow after the new UI update 115.4.2

nick_theboatman — Wed, 27 Dec 2023 22:59:41 GMT

So whats your plan, then?

Re: Thunderbird is extremely slow after the new UI update 115.4.2

Misterjat — Sat, 30 Dec 2023 10:15:52 GMT

Not sure they have one. Do they even bother to read these comments?

Re: Thunderbird is extremely slow after the new UI update 115.4.2

BelFox — Mon, 01 Jan 2024 12:46:42 GMT

I'm on Thunderbird 115.6.0 (64-bit) / Windows 11.

Doing my New Year's mailbox clean-up, I also noticed that bulk deleting or archiving mails takes a lot of time, making the whole experience rather sluggish.

The process was a lot slower on my Google account than on my Hotmail account, however.
I hope the developers can look into this and speed up bulk processes.

EDIT: Thunderbird froze multiple times during the process 😞

Re: Thunderbird is extremely slow after the new UI update 115.4.2

nick_theboatman — Tue, 02 Jan 2024 22:01:44 GMT

They need kicking.... I'll kick them.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

nick_theboatman — Sun, 07 Jan 2024 22:37:44 GMT

ssage

Re: Thunderbird is extremely slow after the new UI update 115.4.2

nick_theboatman — Sun, 07 Jan 2024 22:40:49 GMT

Message from Wayne Merry:

Wayne Mery

Moderator
Top 10 Contributor

1/3/24, 12:18 PM

more options

Glad you have arrived here for support. Please have a look at the details in the items at https://mzl.la/41P4Fcz. Which ones, if any, match your issue?

p.s. the discussion area at Connect is just that, not a support venue. The discussion posting page at
https://connect.mozilla.org/t5/forums/postpage/board-id/discussions
boldly recommends "If you need help with a technical or performance issue, visit Mozilla Support."

Re: Thunderbird is extremely slow after the new UI update 115.4.2

nick_theboatman — Sun, 07 Jan 2024 22:42:29 GMT

But the problem now seems fixed... don't know what he did mind.. hacky magic !!
Version is now 115.5.0. Guess it did an overnight update....

Re: Thunderbird is extremely slow after the new UI update 115.4.2

radical187 — Sat, 20 Jan 2024 09:52:25 GMT

Thunderbird 115.6.1 is unusable. E.g. when trying to reply to a message, my laptop with 32 GB of memory and Ryzen 7840HS CPU lags so much that you have to wait like 2 seconds after each key press. It's impossible to write any emails with this app.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

1di9 — Sun, 21 Jan 2024 09:27:00 GMT

I do not agree, with an old Intel Core i5-2500K and 16 GB of memory I noticed a preformance improvement in latest release restoring a quite normal behavoiur even on this outdate hardware configuration. Lags are not completely eliminated, but In my opinion, the improvement is evident.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

radical187 — Sun, 21 Jan 2024 09:44:08 GMT

Well obviously Thunderbird settings have something to do with the problem.

For example when I disabled the setting "Enable global search and indexer". I also disabled "Allow Windows Search to Search Messages".

It's now a lot better. But it DID lag massively with those settings on. My email accounts use IMAP so that's another angle to investigate (does the new Thunderbird run worse if accounts use IMAP vs POP3?).

Re: Thunderbird is extremely slow after the new UI update 115.4.2

1di9 — Mon, 22 Jan 2024 14:58:59 GMT

I have those settings enabled by default, I'll try disabling to check for best performance....

Re: Thunderbird is extremely slow after the new UI update 115.4.2

mychataa — Fri, 26 Jan 2024 06:30:44 GMT

I use Windows 11, and the mailbox data is placed on the NAS, because I have different computers that need to use Thunderbird. I use version 115, and it becomes very slow when using it. Whether it is receiving, deleting, or moving mails, it is very slow. I changed it back to version 102.15.1 and it became normal.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

sandipgupta — Thu, 01 Feb 2024 20:24:39 GMT

Yes, same for me. Very slow. Even sending emails take time. Which is very frustrating.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

bjamsterdam — Thu, 11 Apr 2024 08:42:12 GMT

I can't understand what's going on. There are a zillion complaints all over the place about this issue, and I see nothing (anywhere) from TB about a solution or workaround.

What makes this more frustrating... suddenly... and regularly... the slowness completely disappears. But I have no idea why. It has a brain all of it's own.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

mychataa — Fri, 12 Apr 2024 08:03:52 GMT

Has the slowness issue of 115.9.0 been resolved? Because I have been afraid to update, I am still using 102.15.1

Re: Thunderbird is extremely slow after the new UI update 115.4.2

sandipgupta — Fri, 12 Apr 2024 13:16:39 GMT

No, it hasn't. It is still very slow.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

Matt_Germany — Wed, 24 Apr 2024 15:27:45 GMT

Same problem here with drag & drop. Moving emails from inbox to a folder (IMAP) takes insanely long, like ~15 seconds for 5 emails. I'm thinking about moving away from Thunderbird for good (after having donated a couple of months ago 😠). V. 115.10.1 (64-Bit)

Re: Thunderbird is extremely slow after the new UI update 115.4.2

sandipgupta — Wed, 24 Apr 2024 21:15:15 GMT

What do you have in mind Matt? I also want to move away from Thunderbird.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

Matt_Germany — Fri, 26 Apr 2024 16:52:18 GMT

I looked around yesterday, but there isn't much choice that appears better. Thunderbird has the cross-platform advantage, but apart from that, MS Outlook isn't bad and performance is definitely better. Everything else I found did not really convince me. 😑

Re: Thunderbird is extremely slow after the new UI update 115.4.2

sandipgupta — Mon, 29 Apr 2024 12:51:15 GMT

Thank you Matt! I shifted from MS Outlook to Thunderbird as Outlook was not able to handle lot of emails. So, I guess I need to stick to Thunderbird.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

IMbzee — Thu, 09 May 2024 17:56:26 GMT

I am also having this problem on my Windows 10 computer since December or early January. Interestingly, it has NOT occurred on a Windows 7 computer I frequently use. Both machines are running the 32-bit version. I notice it most when going through emails in my inbox, which I do daily. I typically keep about 15 emails in my inbox that are action items for the near future (most of which are starred so I can sort them to the bottom of the list). With only this many emails in the Inbox, speeds are almost normal, but once it exceeds this, I start to get several second delays in loading (not downloading, but waiting for the message to display in the preview pane - I almost never actually open emails), and in displaying the next message after dragging a message out of the inbox to another folder. The header from the email I just moved lingers over an empty message box for several seconds before the message I have selected in the message list displays.

I have also noticed occasional improvements, usually after I have signed out of Windows and signed back in, or rebooted completely, but after awhile, the problem always comes back, which makes me wonder if there is some kind of caching issue and the cache is becoming full, and not emptying automatically as intended. I suspect there may be some kind of underlying Windows issue, as I am experiencing something similar in another program.

Since Mozilla apparently ignores this forum, perhaps other participants with a deeper knowledge of Windows can speculate on what might cause this kind of issue?

Re: Thunderbird is extremely slow after the new UI update 115.4.2

max__ — Thu, 20 Jun 2024 14:39:03 GMT

Same thing here... I'm watching this thing since the update in November. I have a Intel(R) Core(TM) i9-14900K and 96GB RAM. Thunderbird is laggy as hell, especially if i leave it open a few hours. It becomes completely unusable to a point where gnome asks me if i wanna force-quit it.

I tried to search in the bug database of Thunderbird, but did not find anything. Is anyone aware of a bug tracking issue?

Re: Thunderbird is extremely slow after the new UI update 115.4.2

SLCompulsion — Sat, 27 Jul 2024 13:07:18 GMT

I don't know what has happen but I am having the same, incredibly slow issues. I'm on 115.13.0, Windows 10. It takes 30 seconds to delete an email! During that time, TB becomes totally unresponsive. I've tried compacting folders but no improvement. TB is unusable. I've used TB for well over 10 years I'm sure. Never had this issue before.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

1di9 — Sun, 28 Jul 2024 07:09:56 GMT

I've installed TB 128 and appears to be really faster than 115. I Hope this will last....

Re: Thunderbird is extremely slow after the new UI update 115.4.2

SLCompulsion — Sun, 28 Jul 2024 10:31:07 GMT

I am now seeing that it is only slow in one account and only in the InBox. I've compacted. I delete the Global Database to re-index based on this: https://support.mozilla.org/en-US/kb/rebuilding-global-database

Re: Thunderbird is extremely slow after the new UI update 115.4.2

sandipgupta — Tue, 30 Jul 2024 21:04:35 GMT

Yes, I installed TB 128 too and you are right @1di9, it does appear to be faster than TB 115. Thank you for the suggestion. Let's see how long it lasts.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

Gawd — Tue, 08 Oct 2024 05:03:28 GMT

I'm on 128.3.0esr (64-bit) and sorry dudes the news is not good. I've been using TBird since Netscape was new and here I am today for the same reason as you. It's been getting worse over the last couple of updates. No one seems to know why or how to stop it.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

R3D_B34RD — Thu, 17 Oct 2024 03:05:46 GMT

If any one is still having issues, it seems to be a MS Defender issue. Check link, fixed the lag issue I had.

https://support.mozilla.org/mk/questions/1413274

Re: Thunderbird is extremely slow after the new UI update 115.4.2

wsmwk — Thu, 17 Oct 2024 13:31:28 GMT

"Allow Windows Search to Search Messages" is known to slow things down, and is cited in https://wiki.mozilla.org/Thunderbird:Testing:Memory_Usage_Problems item #11

Re: Thunderbird is extremely slow after the new UI update 115.4.2

mychataa — Fri, 18 Oct 2024 01:38:46 GMT

me too, I've installed TB 128 and appears to be really faster than 115

Re: Thunderbird is extremely slow after the new UI update 115.4.2

rsbrux — Mon, 02 Dec 2024 14:39:59 GMT

I found 115 to be slow, but I find 128.5 even slower:

https://bugzilla.mozilla.org/show_bug.cgi?id=1906482

Re: Thunderbird is extremely slow after the new UI update 115.4.2

rsbrux — Mon, 02 Dec 2024 14:41:25 GMT

This isn't a Defender issue. I am running Ubuntu Studio 24.04.01 LTS.

This is a bug which has been documented under Ubuntu:

https://bugzilla.mozilla.org/show_bug.cgi?id=1906482

Re: Thunderbird is extremely slow after the new UI update 115.4.2

wsm — Tue, 21 Oct 2025 19:06:46 GMT

Last touch point, a year ago, several people indicated 128 is better. Now a year later, the current esr 140 should be even better than 128 was. And at least one person in https://bugzilla.mozilla.org/show_bug.cgi?id=1906482 is better.

Is anyone better, or worse?

If worse, please do https://wiki.mozilla.org/Thunderbird:Testing:Memory_Usage_Problems and report back. Thanks.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

rsbrux — Wed, 22 Oct 2025 06:55:45 GMT

140esr is working fine for me.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

mychataa — Thu, 23 Oct 2025 00:52:13 GMT

me too.

Re: Thunderbird is extremely slow after the new UI update 115.4.2

wsm — Fri, 12 Dec 2025 00:56:19 GMT

For anyone with imap accounts on 140 and seeing slowness, please post details of your situation in https://support.mozilla.org/en-US/questions/new/thunderbird and state that you are using imap and version 140.

For anyone with pop accounts using 115 or newer and seeing slowness, please post details of your situation in https://support.mozilla.org/en-US/questions/new/thunderbird and state that you are using pop and your version number.