Each time the specified interval (or time-out value) for a given timer elapses, the system notifies the window associated with the timer. Because the accuracy of a timer depends on the system clock rate and how often the application retrieves messages from the message queue, the time-out value is only approximate.
If you need a timer with higher precision, use the high-resolution timer. For more information, see High-Resolution Timer. If you need to be notified when a timer elapses, use the waitable timers. For more information, see Waitable Timer Objects.