Good free anti-virus

I have read most of reviews and can't agree with most of them. I had no problem with Avast, no slowing down my computer or any other problem. Protection is quite good, compared to another similar anti-virus tools.
There are some features I like such as Rescue disc or testing security of home network. There is nothing so important I don't like to mention here.
All in all, good free anti-virus tool.
I am using version 17.4.2294.