Is speed though the limiting factor in elite level hurdling? Look at Devers for females or Trammel for males… I’m not so sure.
There are a lot of ways though in hurdling you can get “overspeed” effects in that you will be racing faster than race speeds. Most obviously lowering the hurdles slightly, but also through zones (take out a hurdle part way through–a technique used by Wilbur Ross) and other pattern changes.