Your laptop's best free antivirus

What's your laptop's best antivirus? Many of us have bought antivirus in the past, only to find that it really doesn't work for our laptops and we may feel like uninstalling it.  Sometimes, the problem is that the antivirus you paid for may not actually be doing the real work it's supposed to be doing. many laptop users have complained that their antivirus makes it hard for them to use their laptop with ease.  Did you in the past have the same problem? If so, how did you deal with the problem? For me, Bitdefender antivirus has been really good for my laptop and I don't even bother about updating it, since it does so.  Secondly, it's unlike the others that you may use for free in one month and then in the next month, you'll be asked to pay for it. It keeps working free for as long as you install it on your laptop without intruding on your work at all.