Rather than "shadowed", I should use the word "transparency", i.e. everything in Unity that has a transparency effect gets temporarily replaced with a rectangular zone that shows flashy/fuzzy artifacts, and this apparently happens when the system is under heavy load - not heavy graphical load, but heavy CPU/disk load...
Rather than "shadowed", I should use the word "transparency", i.e. everything in Unity that has a transparency effect gets temporarily replaced with a rectangular zone that shows flashy/fuzzy artifacts, and this apparently happens when the system is under heavy load - not heavy graphical load, but heavy CPU/disk load...