Keeping speed while three stepping in hurdles?

I do the 110m hurdles and my form is good i have no problems with my lead leg or trail leg except sometimes when i go over the hurdle with my trail leg to low but i can fix that when i really try and focus on it. My problem is that even tho im not a slow guy and preety decent at sprinting when i three step it seems to be slow or i think my three stepping is becoming slower the more hurdles i go over. How can i fix this please?