Methods and systems are disclosed for measuring performance event rates at a computer and reporting the performance event rates using timelines. A particular method tracks, for a time period, the occurrences of a particular event at a computer. Event rates corresponding to different time segments within the time period are calculated, and the time segments are assigned colors based on their associated event rates. The event rates are used to display a colored timeline for the time period, including displaying a colored timeline portion for each time segment in its associated color.