a method of testing a network comprises the steps of parsing a cell from the network and obtaining network performance data based upon the cell . the method calls for evaluating a condition of a live memory flag and storing the network performance data in a first memory if the live memory flag reflects an affirmative value and storing the network performance data in a second memory element if the live memory flag reflects a negative value . the steps of parsing , obtaining , evaluating , and storing are repeated to test the network at speed . advantageously , a method according to the teachings of the present invention permits at - speed collection , calculation , and storage of network performance data as well as capturing a coherent set of statistic at desired intervals . the method disclosed herein is well suited to testing atm networks .