I recently installed ubuntu 18.04 and when playing videos on youtube they freeze for a second or two but the sound continues and then the video continues again for a while, unless you move the mouse then it goes back to playing the video. This happens in chrome and chromium. It stops if I disable hardware acceleration. However then I get screen tearing. Firefox has screen tearing without changing anything. Another side effect of turning off hardware acceleration, is that there is screen tearing and stuttering on websites when scrolling.
I have tried using xubuntu live USB and the freezing problems go away. I also tried it on wayland and the problem of freezing and screen tearing went away but it seems to have performance issues and has occasional stutters and the scrolling is jumpy.