So I got a new machine. Windows 11. Brand new. It's stuck updating. It is taking ages. Why? Well, I don't have any definitive answers but my most basic instinct is to always attach a profiler -- I recommend the excellent @superluminal .

It turns out that there is this thing in the background, TiWorker.exe, and it's taking its dear time while burning through CPU cycles. This is part of the "Windows Module Installer" service, which handles updates.