1. A method for determining one or more performance metrics for a distributed application in which distributed application data are transferred from a first site to a second site over a network, comprising the steps of: (a) enabling a user to transmit a request for the distributed application data desired by the user, said request being transmitted from the second site to the first site over the network; (b) in response to the request, transmitting the distributed application data from the first site to the second site over the network, if the distributed application data are not already accessible at the second site; (c) including machine instructions that define a performance monitoring function with the distributed application data that were requested and transmitted over the network to the second site; and (d) executing the machine instructions at the second site, to implement the performance monitoring function and to determine the one or more performance metrics for the distributed application without using the performance monitoring function to request any distributed application data from any other site.