Windows Defender is probably one of MS' best innovations for modern Windows systems. Originally Defender kind of sucked, but it has grown to the point that it can handle a lot of malware threats, especially stuff that's been in the wild for a few months. It's a huge target for malware authors, but at the same time, MS is actually doing a good job of updating it.
I used to recommend stuff like Kaspersky (lol) or even Avast years and years ago when Defender wasn't as entrenched as it is. Now a lot of commercial products do very little other than hook into Defender or provide protection that is really no better.
MS has created so many loopholes and vulnerabilities in their own OSes over the years that it's about darn time they took responsibility for securing their own OS.
Recently I had a relative click on a malicious link in an email. Of course the site loaded a bunch of crap onto her Win11 machine when she clicked the link. The Defender service held up - almost - and seemed to have prevented a serious infection, though some core OS components were damaged to the point that it was not feasible for me to recover the install. I had to do a fresh install (repair installs weren't working, and eventually the OS became unbootable). But the main thing is, ClamAV and other "offline" scanners couldn't find any malicious files remaining on the drive even after the attempted infection. It's unlikely that sensitive data was scraped off the drive (there wasn't much, but there was a little). Defender kind of did its job.
For expert users on Linux, of course Defender seems like undesirable cruft. But under normal circumstances, Defender comes with a lot lower overhead than standard McAfee/Norton-type AV services, and its being updated by the jerks who created (and continue to create) vulnerabilities for Windows in the first place.
It's odd that Defender would be playing badly with Intel CPUs. MS and Intel need to put their heads together to fix the problem ASAP, assuming they haven't done so already. Nice of Glynn to do something about it in the meantime.