Anyone know how to fix the lag when talking to a driver on a traffic stop? When I get within a few feet of the stopped car my game starts to get very choppy and the frame rates drop. I start walking back to the cruiser and everything is fine. 

This should be resolved when the next version of Traffic Policer is released. Alternatively, if you have a backup of the previous GTA version, you can roll back to that and the previous working RPH. Rockstar made some changes to how certain parts of the game operate in the most recent update which, in some circumstances, causes these performance problems.