A method for accurately measuring one or more network performance statistics during one or more sampling periods comprises processing a received data packet to identify flow information and time of arrival; transmitting the data packet, along with metadata comprising the flow information and the time of arrival, to a sample processing module; replaying the reception of the data packet based on the relative speed of the transmission link and the databus and the time of arrival; incrementing a number of bytes received for the data packet for a first sampling period; starting a second sampling period at a predetermined time and incrementing a number of bytes received for the data packet for the second sampling period, if the replaying is not completed. The number of bytes received for the data packet for the first and second sampling periods are processed into first and second sampling period statistics, respectively.