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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.

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 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?