Hmm. I have been trying https://www.youtube.com/watch?v=HSsqzzuGTPo And I see the major difference between chrome and Firefox. With latter being way easier on the system. Maybe this could be the case. Thing is, that GTM doesn't work in Firefox. So I cannot compare them. It doesn't explain how come that after moving from X230 to Dell 7290 GTM started to be such a problem.