The above table indicates the change in the average pace call at various synthetic tracks and distances from the dirt tracks they replaced.  Positive (+) numbers in blue indicate the pace call is faster than the same call was on the dirt track, while negative (-) numbers in red indicate the pace call is slower.

For example, Dmr 6.5f races were 0.44 seconds slower to the pace call on polytrack than on dirt.

The times represent the pace time of the WINNER of the race, not the leader.  For races less than 8.0 furlongs, the pace call is the 4f, or 1/2 mile, mark.  For races 8.0 furlongs or longer, the pace call is the 6f, or 3/4 mile, mark.

One note, Keeneland not only installed polytrack, but also eliminated some banking from the track.  Since the pace calls always involve turns, this most likely makes the differences appear greater than they would have been with a surface switch only.