From UT Bay:
Desktop Stopwatch is a simple stopwatch which can be used for measuring the time interval between two events, the time you have spent for a project on your computer, to check how fast a program runs or anything else you can think of. You can start the timing pressing the button "Start". The precision is in centiseconds. When you press the button "Stop", the stopwatch takes the time from the computer timer, which is more precise from the time on the screen, so the question of the precision is related only to the problem how fast you can press the buttons.