Anytime you run a program on your computer, this uses up some of the machine’s processing power. The CPU (central processing unit) on modern machines is designed to handle a lot simultaneously. Typically, you can run multiple programs without noticing a difference in the computer’s performance. Keep in mind that some antivirus products are more efficient than others. If you are most concerned about computer speed while the antivirus software is running, be sure to check out the reviews for each product. You can easily compare the data and make sure you are getting the product that is right for you.