The Performance Monitor branch displays the Performance Monitor, which provides you with real-time reports on how various system settings and components are performing. Each item is called a counter, and the displayed counters are listed at the bottom of the window. Each counter is assigned a different-colored line, and that color corresponds to the colored lines shown in the graph. Note, too, that you can get specific numbers for a counterthe most recent value, the average, the minimum, and the maximumby clicking a counter and reading the boxes just below the graphs. The idea is that you should configure Performance Monitor to show the processes you're interested in (page file size, free memory, and so on) and then keep Performance Monitor running while you perform your normal chores. By examining the Performance Monitor readouts from time to time, you gain an appreciation of what is typical on your system. Then if you run into performance problems, you can check Performance Monitor to see whether you've run into any bottlenecks or anomalies.

• If you're using a counter with a significantly different scale, you can scale the output so the counter appears within the graph. For example, the graph's vertical axis runs from 0 to 100; if you're displaying a percentage counter, the Scale value is 1.0, which means the graph numbers correspond directly to the percentages (50 on the graph corresponds to 50%). If you're also showing, say, the Commit Limit counter, which shows values in bytes, the numbers can run in the billions. The Commit Limit counter's Scale value is 0.00000001, so 20 on the graph corresponds to 2 billion bytes.

• You can save the current graph as a GIF image file.

• You can toggle the display of individual counters on and off.

• You can change the duration of the sample (the number of seconds of data that appear on the chart). You can specify a value between 2 and 1,000 seconds.

• You can see individual data points by hovering the mouse over a counter. After a second or two, Performance Monitor displays the counter name, the time and date of the sample, and the counter value at that time

• The horizontal (time) axis now has labels that tell you the beginning and end times of the current sample.