1. A computer-implemented method for displaying performance data for a computing environment, the method comprising: determining values for a performance metric for a plurality of entities that comprise the computing environment; displaying the computing environment as a set of nodes representing the plurality of entities; and for a selected node in the set of nodes, displaying a chart illustrating how a value of the performance metric for the selected node varies over time; wherein a foreground of the chart displays a line for the selected node that represents how an average value of the performance metric for the selected node varies over time, wherein when the selected node is a leaf node, the line represents an average value of the performance metric for the leaf node, and wherein when the selected node is a parent node, the line represents an average value of the performance metric over all leaf nodes under the parent node; wherein the line is displayed against a background illustrating how a distribution of the performance metric for a reference subset of the set of nodes varies over time, wherein the background includes two or more percentile lines for the performance metric, wherein the two or more percentile lines are determined with respect to values of the performance metric for the in the reference subset.