Run up in cricket hellpp plssss?

Ok so you wont believe it but.. when i have a run up the speed at which the ball is released is slowed down. The problem is i start my arm rotation max speed at about half way. but if i do a short run up i focus on arm rotation speed it goes much faster, however then my left arm cannot keep up and is not driven down properly. Likewise i believe my leg cannot keep up with my arm rotation. As taking one step im the fastest bowler in the club. However within a run up im 4th fastest arguebly 5th or 6th.