Recently I switched back from Unity desktop environment to xfce4 and I noticed a screen tearing when watching movies and even slightly when scrolling through websites. Needless to say, it is quite annoying and it should not be happening.
My laptop has a decent Intel core i5 CPU with Intel HD4000 graphics, which should be more than capable of playing back movies perfectly, let alone dispay websites. Hence the newly discovered screen tearing must be a side-effect of switching to xfce4. Initially I thought it was caused by some new driver that got installed or rather replaced during the switch, but there were no signs.
lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
dpkg -l | grep intel
ii xserver-xorg-video-intel 2:2.99.917+git20160325-1ubuntu1.2 amd64 X.Org X server -- Intel i8xx, i9xx display driver
Solution
After scouring the internet for possible causes such as malconfigured xorg config or wrong drivers and trying to fix these, I saw vertical sync mentioned somewhere and enabling it might help. In xfce4 this feature is found in Settings/Window Manager Tweaks/Compositor/Synchronize drawing to the vertical blank, see in the screenshot below.