I purchased a license of a proper antivirus software to avoid that bug and the performance issues gone away.
When you install another AV software, Windows Defender steps down and leaves scanning to the 3rd-party security solution. I selected one of the most lightweight ones I could find. It has been a net win for me.
One shouldn't need to do this, but it has worked so far, for years now.
Which is that? For years (and come to think of it, this goes back to the 2000's or even 90's), AV / antimalware software comes across as scareware, using tricks to ensure you're afraid of not having it.
And second, who here has ever had a virus in the past ten years?
https://www.av-comparatives.org/tests/performance-test-octob...
https://www.av-test.org/en/antivirus/home-windows/windows-10... (less useful..)
AV comparatives has some other tests also that might be of interest to HNers:
https://www.av-comparatives.org/tests/uninstallation-test-20...
https://www.av-comparatives.org/tests/false-alarm-test-septe... (reason why you might not want to pick the fastest product..)