Try removing the first and fourth frame, if you want it to be faster.

Didn't Use any reference, and I see your point on the hip motion, but the shoulder movement shouldn't be back and forward, since the arms remain in a layback position, and the torso staying still (non counting the up an down), I'll definetly work on the hip motion, but as I'm currently trying to reduce frames, to make it look faster, I doubt that the final hip motion is going to be big.

the biggest problem i see here with your animation is your hips and shoulders stay completly stationary, your shoulders do a bit of a bounce but have no forward s backwards motion, the hips should be opposite from the shoulders but also moving up and down and forward and back in a circular like fasion. did you use any ref?

If you are going for the "fast ninja run" here, lower the fps. It would look like he's running way past average speed.

Cool,