[Batfish]

Based on your video, I'd have to say you've got some binding somewhere. That truck should have rolled down the first incline at least as fast as it rolled down when you held the board up high later in the video.
Definitely check the bearings in the truck.
I'm not too familiar with the Savage, but I do know that some vehicles don't like the wheel nuts tightened down too far. For instance, if I tighten down the wheel nuts on my T4 too far it will actually compress the parts on the axle into the bearings and stop the wheels from spinning freely. What I'll usually do is tighten snugly, then back off about 1/4 turn, making sure that the nylock part of the nut is still firmly engaged. Again, I'm not sure if this is applicable to the Savage, but it's another thing worth checking.