The performance of a computer system depends on how the system uses and allocates its resources. Monitor the performance of your system regularly so that you know how it behaves under normal conditions.
The following system resources affect performance:
The CPU processes instructions by fetching instructions from memory and executing them.
I/O devices, for example network connections, transfer information in and out of a system. I/O devices also include terminals, keyboards, disk drives, and printers.
Physical (or main) memory is the amount of random access memory (RAM) on the system.
Monitoring System Performance describes the tools that display statistics about the activity and performance of your system.