Feedback after the update from Ubuntu 13.10 to 14.04 LTS – Video tearing problems
The installer completed the update without any noticeable problems.
After the computer rebooted, my auto lightdm login settings brought me directly (as usual) to my XBMC welcome home screen.
However, I noticed that my HDMI video output was sluggish, with a lot of video tearing (http://en.wikipedia.org/wiki/Screen_tearing).
After a lot of research, I discovered that a bug with libsdl was causing this.
Solutions can be found here :
I personnally chose to update the library, cf : http://askubuntu.com/a/456778/172136