If your graphic card is etc. 2007 and newer, try uninstalling xserver-xorg-video-intel and use the builtin modesetting driver (xserver-xorg-core) instead.
i tried to uninstall it at previous installation of debian 10. now, after os reinstall, i want to compare them.
particularly, i feel video playing in youtube uses much cpu, compared with windows, i want to compare that, whether it is better after removing xserver-xorg-video-intel. maybe i will try to check a video with same resolution and speed and player size, and see it in top... (and write values down and then compare). but if i put it in fullscreen, and see top, it may show incorrect value... it should be correct if i log in other tty using ctrl+alt+fN and run top there.