There are obviously people who cheat on Battlefield 4. They are either using Aimbots or Triggerbots. The instantaneous kills they score is simply humanly impossible. They would appear from out of line of sight and the killing burst or shot would be instantaneous. I am not a good player but I am sure that I am the victim of a number of cheaters. My ping times aren't terrible, it wouldn't be lag.
I saw that three thousand accounts have been banned on Battlefield 4 so far, at least according to a site that I saw. According to the same site, forty-three thousand accounts have been banned on Battlefield 3.
I went to a site which describes different types of cheats. It is appalling as to the number of types of such programmes available and employed. The site advised cheaters not to be obvious about their cheating as the cheaters can get reported and banned. I hope the makers of Battlefield 4 can find the means to clamp down most of these cheaters. Cheating spoils the game for everyone.