A circuit and related method of monitoring performance of an integrated circuit is provided comprising: using a variable oscillator that has an oscillation time period that varies within an expected range with variations in one or more of process, voltage or temperature to provide a signal that causes a count of a first counter to change at rate proportional to an oscillation frequency of the variable oscillator; using a clock source that has a frequency that substantially does not vary with variations in one or more of process, time or voltage to cause a count of a second counter to change at rate proportional to an oscillation frequency of the clock source; setting the second counter to start a count from a start; determining when the first counter has counted a reference count; and providing as a circuit speed, a value indicative of a count value produced by the second counter at about the moment when first counter finishes counting the count interval.