Same issue here, SB3 13.5" i7/512/32
Throttles to 0.19GHz a lot these past days. Started happening during gaming, but activity doesn't even have to be that intense now; this started happening in a Zoom call, and while playing 4k video files in Adobe Bridge. This happens both off and on the
charger, and on the dock (1) with one 4K monitor connected.
Sometimes detaching the tablet portion will make it temporarily stop throttling.
Reboot with the power button + Volume down button seems to always work to get it back to normal, but yes Microsoft should get to work on that firmware update. Seems like the same issue the SB2 and SP6 had with the devices throttling to 400MHz.
I'm guessing this affects only the 13" model since the 15" has a fan in the tablet?
That fixed it for me! Rebooting with the power button + volumne down (hold both until you see the windows logo) fixed it finally. I was going to lose my mind running at 0.19GHz and only one CPU (~13%).
Thank you!