Thanks for the effort. There are still hiccups especially when I move the arrow around the screen. That is at certain specific moments, probably when track loading takes place or there is competition over CPU priority. Something like that.
Also a new OS-X version since yesterday that I have not installed. (yet).
..On batteries it is slighly better than on mains not a night and day difference....
FWIW there is a (expected) difference between a charged laptop and a charging one with the power cable connected.