garmin 78 rapid map movement

I have a Garmin 76 and just obtained a 78. While deer hunting this year and using the 78 I was frustrated by the rapid shifting of the map when I was attempting to navigate to my tree stand. The 76 also shifted around but not near as much as the new 78. What gives here? It is almost useless to me when trying to navigate to a waypoint. I realize that the unit needs to be moving at 2mi per hr to be steady but the 78 is worse than the 76 in this. What to do ?