Oh noooooo! FB12122106 still exists in macOS 14.0 (23A344)

https://mastodon.social/@siracusa/110117776662224597

https://youtu.be/h0bKmcsMFvw

I wasn’t able to reproduce it in a clean install of Sonoma, so it's obviously something related to my specific configuration. But damned if I know what it is…

FB12122106 Demonstration

YouTube

Still trying to track down this bug https://mastodon.social/@siracusa/110255326994000695

To review:

1. It happens only when more than one user is logged in.

2. It does not happen on a clean install of Sonoma—but it does happen on my actual install of Sonoma.

3. It happens even when the only two users logged in are two newly created user accounts.

4. No non-Apple KEXTs are installed.

Given all of this, I've been looking in /Library for culprits. Is there some other place I should be looking?

Important update to https://mastodon.social/@siracusa/110255326994000695

The bug *is* reproducible on a clean install of macOS 14.0 (23A344).

It was not reproducible in an earlier Sonoma beta, but that changed some time between then and the release version.

At least I can stop tearing third-party software out of my system now…

…but now it’s time to try removing some hardware…

(Reminder for Apple folks: this is FB12122106.)

I've re-filed this bug against Sonoma specifically (because some Apple folks tell me this is a useful thing to do). Please see FB13211706 for a newly summarized report with new spindumps, samples, a sysdiagnose, and a new demonstration video.
Here’s my new demo video for FB13211706. (Please forgive the awful audio. I had a bunch of stuff on my desk that was in the way of setting up my podcast microphone.) https://youtu.be/5Aq2GZpKkLU
FB13211706: Window dragging is laggy and jumpy when more than one user is logged in

YouTube
@siracusa is there any CPU/message/trace activity on the secondary user's processes while dragging a primary user window? It's as if drag or repaint events are being delivered synchronously to low priority processes owned by that other user?