I am having these same issues of extremely slow processing in the editor, in both Chrome & Safari, & on a new Mac Air M1. It's very frustrating, as I'll often wait 10-30 seconds simply to delete/replace a word. I don't even have any images or media on the site, all just text. Even worse, the entire page will continually crash (getting the Chrome 'aw snap, something went wrong... message), so I then have to reload the site, losing all my edits. Squarespace is almost unusable for me.