Is this something related to the latest Windows 10 updates or it was always the case? I mentioned this because, may be unrelated, there are some slow drawings in the UI after the October major update. I can notice this when I login and the desktop is drawn.
The article mainly explores the difference with DWM (Desktop Window Manager) enabled and disabled. DWM's main role is to render all of the windows into separate buffers in memory and then "compose" them on the fly. This for example avoids the effect that dragging a window over a frozen application would result in glitches.
Since Windows 8 DWM can not be disabled. By default in W7 it is also enabled (the infamous Aero), but at least you can get rid of it.
