Navigate to the area of the app that you're interested in assessing memory usage, such as the main level of a game, or the primary editing operations of an image editing app.

Use the app for a few minutes to allow Instruments to retrieve a representative sample of data.

Select a range spanning the time within the run you want to analyze. Doing this filters the results shown on the Allocations Summary below.

Figure 1 – Hold the Command key and click from areas marked 1 to 2 in order to select the range of interest.

Figure 2 – Include in the range ramps that represent allocation. The range shown here includes allocations for a game's intro screen and loading the first level. These two events were chosen because they allocate a majority of the total memory used by the app, and therefore, they are also the best candidates to speed up.