Today’s USA update screwed up a lot of things, unfortunately.
With regard to the stuttering, there seems to be a memory leak somewhere and 2020 will devour however much memory is placed before it, regardless. You’ll notice the stutters more when you restart a flight without restarting the sim.
It is better than it used to be but on takeoff and landing, unless you have flown the route before (rolling cache) you may well find the stuttering to be more obvious.
Restart the sim and fly the route again and you may find that the stuttering is either gone completely or at least reduced.
Hope this helps.