A challenging problem in software testing is finding the optimal point at which costs justify the stop-test decision. In this paper, we first present an economic model that can be used to evaluate the consequences of various stop-test decisions. We then discuss two approaches for assessing performance, automated load test generation in the context of empirical testing and performance modeling, and illustrate how these techniques can affect the stop-test decision. We then illustrate the application of these two techniques to evaluating the performance of Web Servers that performs significant server-side processing through object-oriented (OO) computing. Implications of our work for Web Server performance evaluation in general are discussed.