Using a slow computer can be very frustrating; and, since there is a laundry list of things that can cause your computer to slow down, you may have a difficult time troubleshooting the problems. Slow computers can be filled with viruses or malware, they can have too many applications running in the background, or they could just be getting old. If your computer is relatively new and in healthy condition, but is starting to slow, one upgrade can make a big difference.