Digital Foundry has taken its mathematical approach to examining the deep inner workings of games to whole new heights with is recent lag analysis of the Killzone 3 multiplayer beta. Using a special controller (designed by modder extraordinaire Ben Heck), the DF team measured the exact amount of time that passed between pressing R1 and the in-game gun actually firing a bullet: 116ms. According to the blog, that's about 33ms shorter than the lag present in Killzone 2, which apparently makes a world of difference in twitchy shooters of this ilk.
Check out a video of the group's study, as well as a few other odds and ends about the technical side of the beta, over on Eurogamer.