Gauges are lightweight processes that monitor your app's use of CPU, memory, graphics, and other resources. The gauges appear at the left. Clicking on one brings up a more detailed view at the right. If you need a more thorough analysis of the problem, you can click on the "Profile in instruments" button, which launches more powerful analytic tools that take a deeper look at the code as it runs. However, they are much more intrusive than the gauges.