I find I've only had this problem on this map. I was getting it on other maps too, but I used the engine.ini fix that someone posted on Steam, which has just narrowed it to the 1 map.
Constant stuttering, only on Precinct.
Generally it's been getting worse since the last update for some reason, and I checked the ram-use of the game now, and for some reason it's using 10gigs of ram and it's only going up, so the game must have a MASSIVE memory-leak