Even if 3rd party software like System Informer, Process Explorer, MSI Afterburner, etc. were working ok... Windows Task Manager was also displaying 100% CPU usage.
And this solution finally fixed it for me...
Windows 11 Insider 25267
Task Manager says the same as System Informer. The system was doing practically nothing when I took those screenshots.
Weird thing is that it works ok in another machine with the exact same Windows 11 Insider version and same Ryzen 9 3900X cpu.
HWinfo is wrongly displaying 100% CPU usage on my Ryzen 9 3900X with PBO
Real CPU usage was less than 6% at this point:
This is being happening to me in several versions, both stable and beta.