This might be a blockbench issue but the animations in blockbench run smooth.
In game my entity (nightmare horse) works great. The animations all work except the legs move very slow while the horse moves very fast and I cannot figure out how to speed up the animation in game.
The other issue is the entire body of the horse shifts upward and then back down within a blink and it looks very glitchy. It only happens while walking and happens every 5 seconds or so. Not even sure if I should include video or not.