Today my co-worker noticed that when adding a decimal place to a progress indicator leads to the impression that the program is running faster than without. (i.e. instead of 1,2
This effect can be very dramatic: doing relatively large amounts of work to give users a correct and often updating status of progress can of course slow down the actual running time of the application (screen updates, progress display needed calculations, etc) while still giving the user the feeling it takes less time.
Some of the things you could do in GUIs: