Having installed Win11 on a PC with a 3570K it ran just fine. I don’t really see a difference in performance between 10 and 11 on desktops. I have an old ThinkPad with an i5 6300U and performance on that isn’t amazing, but I’ve never used 10 on it (bought it from the company I work for last year) so I don’t know if it doesn’t like 11 or that’s just how it is.
“over time” is key in the description of how this works. I went on a work trip with a colleague recently and it was only about 24 hours after we met up that my phone notified me there was an AirTag following me, because she had one on her car keys. You wouldn’t be notified straight away.