One of many problems with this particular set of symptoms is that their causes aren't confirmed. I even have two test machines here with IDENTICAL hardware that were both clones of the same install of macOS and one exhibits problems while the other doesn't at all, even in the exact same file.  This isn't intended at all, but this weird redraw lag and intermittent nonresponsiveness is new. There are things you can do to mitigate it and things that may exacerbate it (both categories discussed i