Throughout the recent stress test I got great fps, but I noticed that over time a bad stutter developed. It would most frequently happen after firing a weapon for the first time in a while, which is a very critical time for the game to run smoothly. I pulled my pistol on a close range survivor and fired and the game froze for a full 3 seconds. Of course I was killed. After this I started paying attention to how frequently the game did in fact stutter. Too much is the answer.