Comment # 4 on bug 1187259 from Stefan Dirsch

I think you need to enable TearFree here.

# man xorg.conf
       Option "TearFree" "boolean"
              Disable or enable TearFree updates. This option forces X to per-
              form all rendering to a backbuffer prior to updating the  actual
              display. It requires an extra memory allocation the same size as
              a framebuffer, the occasional extra copy,  and  requires  Damage
              tracking.  Thus  enabling  TearFree  requires more memory and is
              slower (reduced throughput) and introduces  a  small  amount  of
              output latency, but it should not impact input latency. However,
              the update to the screen is then  performed  synchronously  with
              the vertical refresh of the display so that the entire update is
              completed before the display starts its refresh.  That  is  only
              one  frame is ever visible, preventing an unsightly tear between
              two visible and differing frames. Note that this replicates what
              the  compositing  manager should be doing, however TearFree will
              redirect the compositor updates (and those of fullscreen  games)
              directly on to the scanout thus incurring no additional overhead
              in the composited case. Also note that not all compositing  man-
              agers  prevent  tearing,  and  if the outputs are rotated, there
              will still be tearing without TearFree enabled.

              Default: TearFree is disabled.

--> /etc/X11/xorg.conf.d/50-device.conf

Section "Device"
  Identifier "Default Device"
  Driver "intel"
  Option "TearFree" "on"
EndSection