Trzy szachy (3-checks)

Computers actually have two kinds of speed: (...) the real (machine) speed and (...) the perceived speed. Of these two, the one that really matters is perceived speed. For instance, a 3-D rendering program that saves a few moments by not displaying the results until the image is complete will inevitably be seen as slower than a program that lets the user watch the image as it develops. (...) Users will say that the first program ran slow simply because the wait was more painful.

(P.Bickford)