To add to Redsnail's comment, for shorter trips, the use of a turboprop is more efficient. One must also look at the efficiency of the engine itself. A turboprop has a much greater thrust efficiency at lower speeds, up to approx 350-400kt from memory, So on a short haul flight a speed higher than that, would be of little use, for the distance flown.
I hope this adds to you answer.
SUF.