A network performance monitor for a computer. The performance monitor maintains a baseline for communication paths between a networked computer and other networked computers connected. The network performance baseline is established and maintained by measuring and updating network performance parameters of the communication paths. The network performance parameters are updated using values obtained during time intervals when the communication path consumed a bandwidth approximately equal to its estimated bandwidth. If congestion is detected on the network or the network is underutilized, values of the network performance parameters obtained during that interval are not used to update the network performance parameters. Some performance parameters in the baseline, such as minimum and maximum bandwidth values may be updated by computing a moving average of each parameter. Asymmetric weight values for updating the moving average may be selected based on a direction of change of a value of a network parameter.