Before we jump to the next big thing, it is important to protect your online activities. Often, people think that if you use your system just for gaming you won't need an antivirus because all you have are games on your system. That's partially true, but if your privacy is not your problem, then your system's performance is. Viruses can slow down your system a lot, some can destroy it. Get a good antivirus, there are plenty free ones, and a good firewall. In addition, clearing system trash will also erase traces of your sensitive footprints left on your system. If you are sure that you don't have your system infected but want to play games offline, you can turn these off, but always use them when online.