Use the vmstat command to determine where the system performance problems are. vmstat reports statistics about kernel threads, virtual memory, disks, and CPU activity.

Here is the syntax for the vmstat command:

vmstat [-fskIt] [drives] [interval [count]]
Hard drives to monitor (hdisk0, hdisk1, and so on).
The update period. If vmstat is run without an interval, it shows the statistics from reboot. If an interval is set, the first line is the statistics since the system startup, and the next lines show the statistics from the previous line.
Number of iterations.

Reports from vmstat Command