When end-users complain about performance they will say something similar to: “When I click the submit button on this web page, it takes 30-40 seconds.” They use elapsed time as a way to describe the problem, so why not use elapsed time when finding the queries to tune.
The query above will provide a definitive list of SQL statements with the highest elapsed time since instance startup. Often this may be based on a timeframe of several months or even longer, so collecting and saving this data periodically with deltas will provide the best information. For example, running a query similar to the above (along with other pertinent data based on your application) every 10 minutes and saving the data will allow you to go back in time to find a problem. If an end-user complains about performance from yesterday at 3:00 p.m., reviewing the archived data from a