Performance is your reality. Forget everything else.
Only once you have identified the root cause of a performance problem should you try to solve it. As described in Chapter 3, several kinds of problems exist. Regardless of the problem you are facing, the essential goal to achieve is reducing—or, even better, eliminating—the time spent by the most time-consuming operation. Note that a single operation may be composed of many actions that are executed one by one. For example, many fetches are necessary in order to fully process a query returning a lot of data.