I am playing games a lot. I am interested in which antivirus program has best performances for gaming. My pc is little bit low and every save of computer speed is very valuable for me. I am currently using Advanced system care with antivirus 2013. It is good but I would like to try something else to. Thx in advance 
Games don’t write files except when saving, so I’m not sure this actually matters… AV really only affects performance when files are written to disk.
That said, from my experience, the most light-weight AV is Microsoft Security Essentials, which is also free.
In my experience, Microsoft Security Essentials and Avast both work about equally well and have similar performance. I haven’t noticed any performance issues with either one and games.
The only antivirus I have personally noticed performance issues with is Microsoft Forefront, which we are required to use at work. Between Forefront and automatic updates (which we are not allowed to turn off or do manually) they manage to turn my computer into a snail on sedatives. (ETA - Note I don’t play games at work, just noticing performance issues in general)
Automatic updates of both Windows and other programs will often cause performance issues with games. Networked games in particular will be laggy, but even non-networked games can suffer performance issues due to update tasks taking up CPU cycles and tying up the machine with disk accesses in the background. Either schedule your updates to occur at a time when you know you won’t be playing games or do the updates manually so that the are done when the computer is otherwise idle.
That is not necessarily true. Games access the disk (usually doing more reading than writing, admittedly) when you change levels and such. In order to avoid pauses in between levels/areas some games also don’t completely stop and load data for the next area, and instead load the data in the background, dumping unused data as you move away from an area and pre-loading data for the next area as you get closer to it. That way you get smoother gameplay and don’t have to sit there twiddling your thumbs and watching some loading screen.
Unless you’re using a pirated game, where viruses would be a concern, I’d say you should just turn the thing off when you’re gaming.
Problem solved.
This is straying into IMHO territory, but that seems like a really bad idea to me.
Why is that? So long as he remembers to turn the scanner
back on he should be fine.
The scanner should catch any viruses in the interim time between gaming.
I have never heard of a virus that lies hidden until you decide to turn your virus scanner OFF.
So long as he remembers to turn it back on. I’m pretty sure he will be just fine.