Irrespective of the anti-virus application you use. They're all crap IMHO. If they have an option to go "passive" when something launches full-screen it's ok to have on your gaming PC. However it's like wearing a bulletproof vest; it's heavy (consumes cpu, memory and IO time) potentially still slowing you down a notch. It's completely useless if you get shot in the head (targeted malware / day zero exploits).
Your best defense is essentially having some form of virus protection (hell even Windows defender is ok for this), make sure it's configured to run DAILY scans and at least one full traverse your entire file system type scan. Enable you bloody firewall and make sure you know what is allowed to speak IN and OUT from your system. Avoid trusting anything you download from the internet. Don't trust a media source (thumb drive, external HDD, CD/DVD, etc) that you don't own.
I have a Linux machine running ClamAV that I get people to stick their dirty drives into. It runs a scan activity every time a device is auto-mounted.
ClamAV databases are also by Immunet. You can get Immunet here
