Vapor, I think we're not taking about horns being faster than a diaphragm but high frequency being faster than low.
Timing is timing: if this user is finding the timing is disconnected or does not match his horn loudspeaker it seems that there is a disconnect. I recommended a front firing sub placed forward in the set up if possible works like magic.
Horns are faster in the sense that they can increase both the dynamic range and spl by as much as 5db making them seem faster as they are often more in your face.
Q