Exactly as the title says, going in first-person in a vehicle after the update causes constant stuttering and fps drops; along with very choppy sounds. This is a Report on the actual website, but this subject comes straight from the steam discussions : https://steamcommunity.com/app/107410/discussions/0/135511913384223613/

If you don't read it, basically a temporary fix has been found for SOME users to switch their sound in their audio drivers to stereo instead of surround sound. (Some people think it has to do with AMD FX Processors,[which I myself own one], but I, myself, fixed it by changing the audio to stereo, but that was almost unplayable, in the sense that I couldn't hear much, and no sense of direction.)