CPU usage is the amount of processing speed and power that a processor uses at any time. The CPU, or Central Processing Unit, controls all input/output instructions in the system. If the CPU usage runs too high in a computer, it potentially causes slowdowns, freezes or restarts.
Every time a program is opened on a computer, it takes up more RAM and more processing power to keep it running. Processors can only execute one instruction at a time, but they do it so quickly that it appears instantaneous. The processor's power is measured in hertz, or clock cycles per second. This is the number of full input-output instructions it can process. For example, a 2 gigahertz processor can perform close to two billion calculations per second. As users open programs, they place more demand on the processor and make it do more work.
To find out how much processing power a CPU uses, press Ctrl+Alt+Delete on the keyboard to open the Task Manager. Then, move to the Performance tab. A scrolling line graph shows the ongoing usage of the CPU. If the CPU consistently stays at or near 100 percent usage, close programs to make the processor work more quickly and smoothly.