The one example i've experienced, is when coming in steady to land on a moving ship, ONLY while using the Advanced Flight Model. This was not always the case. I will test some more to see if i can reproduce.
-EDIT: Having tested some more, i'm not sure weather the stuttering is consistant. The latter still remains. (Advanced Flight Model issue belew)
Not only does the game stutter when getting in close to the other PhysX vehicle, but the Advanced Flight Model also prevents from landing on another PhysX vehicle, even if that vehicle has properly modeled LOD's for landing.
https://youtu.be/3uo_1kjFZrk - Advanced Flight Model, Vs. Standard Flight Model