I really like the Web performance testing tools built into Visual Studio 2012 Ultimate. These are tools you can use to create and execute automated tests of web applications for the purpose of measuring performance and load. These latest versions are much more polished, feature-rich, and easy to use than the versions that came in previous versions of Visual Studio. One of my favorite features is the ability to export load test results into an Excel workbook.
When you generate the Excel load test reports, there are two different formats available. One is a side-by-side comparison of two different load test runs. The other is a trend analysis that can compare two or more test runs and show a graph of the trends of various performance measures. When you press the button to export the test results, it does not merely dump the raw data into an Excel workbook, it uses Excel automation to generate a bunch of graphs that show the comparisons or trends in the various performance measures. It is the same kind of work that we used to have to do by hand. Only now, thanks to automation, we can see the results in a visual fashion much more quickly.The sample image shown above shows a trend report I ran.
I was testing the performance of a web application with various web garden settings. The first two runs, 44 and 45, were run with the worker process equal to one. Run 47 performs the load test with two worker processes, and run 48 is the performance of the web garden with four worker processes. From my experiment, I concluded that my current configuration would be able to deliver far more results with four worker processes. As an interesting side note, the IIS server that was hosting my web application had four CPUs. So this is a reasonable result to expect. But there is something very satisfying about having actual performance tests data to verify your hypothesis.
If you are interested in learning more, this MSDN article is a good entry point Examining Web Performance Test Results Using the Web Performance Test Results Viewer.