Resolved but confused: Linux, Intel VMD, Micron SSD, btrfs

Hi all, got a new laptop for work - ASUS Zenbook 14 with a Core 9 Ultra 285H. It ran Windows okay but it would shut off with large e2e testing runs. I suspected overheating because it’s a thin laptop, too thin I think. With our Java + Node workflow the 32GB of memory was just not enough for parallel e2e testiung so I convinced them to let me trial Linux instead.

I wanted the potential for team adoption so steered clear of bleeding edge stuff so it was Ubuntu 26.04 and I punted Ubuntu Pro as an option that helps with our compliance which landed well.

Then the laptop started stuttering quite bad, it’d freeze for a good 5-10s - then be fine for a bit. The company sent me a replacement laptop, but since I work remotely, I had both laptops with me for a bit. The new one, which is practically identical (although not technically identical as I’d find out) - worked fine. I used Claude to help me diagnose, and at the end of the rabbit hole, I narrowed it down to the combination of:

1. Micron SSD (the unaffected laptop used a Samsung SSD)
2. Intel VMD enabled in the BIOS (default on)
3. Using btrfs as the filesystem (doesn’t cause it but could make it worse)

Simplest way to resolve it was to disable Intel VMD in the BIOS, and now the thing is flying as expected.

I’m still curious why and hoping fellow Linux neckbeards can help me understand. Claude helped me get to the answer, but while we solved it from a usage standpoint, it’s explanation is quite speculative. So hoping to learn from this community instead.