By default, the Visualization pane shows the whole frame, and the height of the erg bar corresponds to the relative duration of the erg as executed on the GPU. The higher the bar, the more expensive the erg in terms of total rendering time.

To find the most expensive ergs, you can:

You can also select the most expensive ergs by selecting their respective check boxes. Review their impact on the entire frame and on a respective render target in the Render Target Viewer pane, as illustrated in the following figure. Note that the order in which you select ergs has no impact on the results, and that the selected ergs are then used as the target for any future experiments that you perform within this tool.