The CPU is the processing power of your computer. When usage is high, a normally fast computer can slow to unbearable speeds. For some computers, this may be a memory problem, but some people experience high CPU usage from programs that utilize most of the available resources. Checking CPU usage is one of the first steps when troubleshooting slowness issues on a desktop or laptop computer. These steps show you how to view CPU usage through Windows Vista and Windows XP.
Start the Task Manager. Press the buttons Ctrl, Alt and Delete all at the same time. This will show a screen with several options.
Choose “Start Task Manager.” This will open the Task Manager Program window.
Click the “Performance” tab. In this screen, the first box shows the percentage of CPU usage. Normally, this range will remain below 20 percent to 30 percent. However, if high CPU use is slowing a computer, spikes of 75 percent to 100 percent can be seen.