A ASP.NET performance advisors, we are typically brought into a project when it's already in trouble. In many cases, the call doesn't come until after the application has been put into production. What worked great for the developers isn't working well for users. The complaint: the site is too slow. Management wants to know why this wasn't discovered in testing. Development can't reproduce the problem. At least one person is saying that ASP.NET can't scale. Sound familiar?
Some of the busiest Web sites in the world run on ASP.NET. MySpace is a great example; in fact, it was migrated to ASP.NET after running on a number of different platforms. The fact is, performance problems can creep into your app as it scales up, and when they do, you need to determine what the actual problem is and find the best strategies to address it. The biggest challenge you'll face is creating a set of measurements that cover the performance of your application from end to end. Unless you're looking at the whole problem, you won't know where to focus your energy.
The Performance Equation
In September 2006, Peter Sevcik and Rebecca Wetzel of NetForecast published a paper called "Field Guide to Application Delivery Systems." The paper focused on improving wide area network (WAN) application performance and included the equation in Figure 1. The equation looks at WAN performance, but with a few minor modifications it can be used to measure Web application performance.