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At the start of last week Thunderbird started to be very laggy to the point it is almost unusable.

It was after the update to version 151. Running on MacOS Sequoia

I have tried a number of remedies to try and resolve the issue:

• Compacting mail folders
• Repairing mailboxes
• Clearing the cache
• Rebuilding the search index
• Restarting in trouble shooting mode (this caused Thunderbird to hang)
• I also tried installing the daily build release to see if the issue was resolved

None of the actions above solved the problem. I would very much appreciate any help or experience others have had.

Z.

On iGPU hardware, default dedicated VRAM is usually 0.5GB and the maximum is 2GB.

On my laptop Firefox only use 0.48GB(dedicated VRAM)/0.2GB(shared VRAM) when I set VRAM to auto(512MB) in BIOS.

The screenshot is when I set dedicated VRAM to 2GB in BIOS, and you can see the VRAM usage has increased to 1GB(dedicated)/0.5GB(shared).

It seems Firefox is restrict itself to dedicated VRAM and not fully utilize the vast amount of shared GPU memory. This makes sense on dGPU hardware but not on iGPU hardware. On iGPU hardware, the negligible amount of dedicated GPU memory exists only for compatibility to legacy programs, and Firefox should allocate all it's GPU memory from the shared GPU memory pool.

Hi , I am using the MacBook Pro M5 which is running with macOS Tahoe 26.5 . I have installed Thunderbird mail with version 150.0.2 . After the initial installation with only one account with few mails in the inbox I found the App opening time is abnormally high & is more than 1 minutes . I have removed the mail App few times & re installed it ( even I have re download the app from net again) , but the problem remain same .

I have removed the old folder & files from - ~/Library/Thunderbird/ , ~/Library/Application Support/Thunderbird/ , ~/Library/Caches/Thunderbird/ , org.mozilla.thunderbird from ~/Library/Preferences/. before the re installation & re started the laptop , but no improvement in results .

Also in mail setting references → Unchecked the option - Enable Global Search and Indexer Disable all Extensions and Themes under Tools → Add‑ons & Themes (No Extensions is installed) .

Just to inform that the apple mail is working fine in this laptop .

After all the above trails the results are same , the app once quit & re start - it takes around 1.5 minutes to open after which the app works normally with out any problem . Please suggest if any solution is available for this problem . Best Regards Gautam Banerjee

we are using firefox std version in more than 15000 machines in our organisation, recentlty we migrated to all machines to ESR version, but now we are getting escallation, the application working very slow and not opening sometimes

I have a Postfix/Dovecot server that hosts 10 of my domains from one IP.

When you open Thunderbird, it checks the domains you have preset. I have two. This happens immediately, especially if there is no new mail on the server. Everything works fine.

If you have other domain mailboxes open, and I have eight more, and you click the inbox on each one, Thunderbird stalls at the fifth mailbox, regardless of the inboxes' selected order.

tail -f /var/log/mail.log - confirms this.

I have reset or modified everything I can think of. My server is not throttling Dovecot.

This must be something internal to Thunderbird, possibly related to only using a specific mail server IP for all domains.

Google AI suggests assigning a unique local IP alias to each domain on my server so Thunderbird thinks it’s talking to 10 different machines. This seems extreme.

Any solutions?

I have tried for several days to get Firefox to use this GPU; I cannot. Chrome, and Edge use this GPU without issues.

I am using Firefox 151.0 (64-bit) 20260516144017 on Windows 11 Pro 25H2, 26200.8457 Nvidia RTX 2000 Ada Generation Laptop GPU with latest driver: NVIDIA RTX Driver Release R595 U4 (596.36) Tue Apr 28, 2026.

Windows > System > Display > Graphics > Firefox GPU preference: High Performance (NVIDIA RTX 2000 Ada Generation Laptop GPU)

Firefox Settings: General > Performance:

unchecked Use recommended performance settings
 checked    Use hardware acceleration when available

My latest combination of settings are:

gfx.webrender.all = true gfx.webrender.force-disabled = false

webgl.default-low-power = false webgl.disable-wgl = false webgl.disabled = false webgl.enable-prototype-webgl2 = true webgl.force-enabled = true

I have tried several combination of settings to no avail.

I always get: about:support > Graphics > Compositing: WebRender (Software).

Any help is very appreciated -- thank you.

The GPU isn't working properly... I've attached screenshots of the browser I have installed. If needed, I can take any logs, etc. It's very frustrating - I have a fairly old processor and its GPU isn't working properly! If needed, I can create a thread on the forum and attach any information about my system. Sorry if I'm in the wrong place! Best regards, and thank you for the best browser in the world!

I open Firefox and Chrome with the exact same page:

https://en.wikipedia.org/

Chrome is using 296 MB while Firefox is using 590 MB.

What am I doing wrong?

I am running Thunderbird 140.9.1esr on openSUSE Tumbleweed.

For a long time now, Thunderbird often runs at high CPU (80-100% of one core), for several minutes at a time (5-10 minutes). This seems to happen many times every day, with no apparent cause from my end. (I just got back from Lunch, and the fan on my laptop was going crazy because of the high CPU.)

What can we do to identify and fix this issue?

Search in Thunderbird has never worked reliably for me. I've deleted and rebuilt GloDa, and am now monitoring indexing progress in the Activity Manager.

After recently enabling indexing for a couple of additional folders, every time I start Thunderbird it seems to index a few emails (maybe 20 or 30 or so) then hangs, and the indexing progress stops.

My total number of messages in my entire Thunderbird profile, across every folder in all of the few email addresses I have, is a couple of thousand emails. We're not talking anything crazy here.

There are gigabytes of RAM available and hundreds of gigaabytes of free storage space on the local volume.

Any ideas?

Co żeście spieprzyli w tej przeglądarce? Claude AI zawiesza całą przeglądarkę. Od kilku wersji coś jest fundamentalnie zchrzanione bo nawet Pikvm nie serwuje obrazu. Do tego popsuliście coś z profilami, że nie można wrócić do starej wersji przeglądarki. Cała masa błędów. Na siłę próbujecie udaremnić działanie wtyczek blokujących szpiegowanie użytkowników?

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

Thunderbird causes my machine to 'hang' from time to time,

1. often for up to a second and usually a number of times in quick succession on each ocasion. Sometimes this happens frequently - say every 5 or 10 minutes - sometimes only after an hour or more since the past occurrance.

2. My machine hangs completely - nothing will work, mouse, keyboard, sound, other apps etc. If I happen to be typing (into any app - including Thunderbird - when this happens, input ceases, the cursor freezes and - if the problem persists for a second or two, Windows reports "[app] is not responding"

3. I cannot be certain, but I believe the problem occurs whilst messages are being retrieved.

This is a very serious problem as it means that I can never leave TB running as the problems it causes are not acceptable.

4. This means I cannot deal with incoming messages without periodically re-starting TB - which is an utter PIA.

I am running Win 11 Professional on a 2-year old machine with 64 Gb of memory. I have run TB in Troubleshoot mode, I have confirmed that the problem occurs regardless or whatever other apps are running (or none) and I have proven conclusively that no other app causes any kind of similar problem.

Looking forward yto hearing if others have had the same issue and what can be done about it.

Unable to open NEW Email on one click. i need to wait for 4-5 mins to open that email. even i am not able to open on one click which contains Barcode. which email contain barcode its also not reflecting in email and even i need to wait for 4-5 mins to open that email.

Kindly help me for this matter i need to change any settings.

Anyone else had problems the last two weeks with performance? I'm on a macbook (Tahoe 26.3.1) and in the last two weeks tabs are constantly crashing or freezing. I have never had this before. It's doing my head in and I'm about to make the painful move over to Chrome if nobody has any ideas how to fix it?! I don't want to do that as all my bookmarks etc are set up on Firefox...

bold text On brand new DELL Alien-ware laptop with Windows 11 Firefox sometimes takes 30 seconds to open, Also once it is closed it cannot immediately open again. Error message shows Firefox is already opened and asks me to close it.

In the task manager under Apps running I see Firefox(12) when only the home page is open. Are those 12 hidden tabs or 12 parallel applications?

Have I made some errors in the Setup?

I am running an iMac Catalina 10.15.7. Since Firefox just updated itself my system keeps crashing so bad that I have to do a hard shut down. Yesterday I had to do this over a dozen times to get through my session. Firefox was the last browser compatible with my Mac. Is this no longer the case?