When Madara first activated Limbo, all the Bijuu were knocked out instantly and simultaneously.
This means the Shadow Madara must be extremely fast.
Shadow Madara sprinted the length of several football fields to the Bijuu and attacked them all in less than a blink of an eye.
Well, Shadow Madara is basically a ghost and ghosts should have no mass. This means the shadow should be able to move at relativistic speeds( i.e close or at the speed of light)
Just imagine how fast Sasuke and Naruto are for even being able to keep up.