The GameBryo Engines all use an obtuse animation speed leverage -> it averages the Distance Traveled, Duration and Size of the Actor in relation to the Sequence being played to get an averaged Units Per Second Movement Speed
This is why Mehrunes Dagon can not move even if you give him movement animations as Very Large Creatures get their movement speed culled to basically zero -> I had to rescale Akatosh 3 times just to get him down to a size that the game would allow to move and even then I have to set his speed to 130 to get the animations to play at 1.0 frequency.
Very Small creatures on the other hand like my Slimes get their speed increased drastically so to get them to play their anims at 1.0 I had to set their speed to 5 otherwise they moved around at mach 2.