System Monitor
You use System Monitor to measure the performance of your own computer or other computers on a network. System Monitor uses a series of counters that track data, such as the number of processes waiting for disk time, the number of network packets transmitted per second, and the percentage of processor utilization. With this data, you can create charts, set alerts, and format reports that enable you to gauge and tune system performance. Data can be displayed as it is collected, stored in log files for later use and comparison, or both.