What is a good approach for a performance testing tool suite for web applications? I am specifically interested in tools that execute a certain set of tasks well as opposed to tuning high traffic sites. In other words, a profiler would be a good idea to have, although I understand these tools are specific to a language. A profiler will help me understand where most time is spent in executing a particular part of the code, but does not provide me with a start-to-end view of where performance could be improved. Is there a tool that provides profiling data on where in the chain browser, web server, application server, database server most time is spent?

Thanks in advance