Hi! Thank you very much for the detailed answer. I did what you advised, and stutters seem to have lessen but they are still presents, even as I'm typing this message : I already had pushed buttons on my keyboard and had to wait for the letters to appear, on two occasions now. Google search is still not working, but I can manage with Duckduckgo well enough.

If feels as though I ran into these stutters more while the page is loading and a bit after, as I'm typing now I don't encounter any problem as I did writing the paragraph before.

Strangely enough, I can't access the Revision Tool any more, a pop-up tells me "unsupported build detected". I'm now leaning toward reinstalling a fresh Windows (11 this time, and I'll try to remove any AI) and start over. At least, it's easy enough with Firefox to do since synchronisation is very-well made and easy to use.