In 1/2mv^2 for a given amount of energy from the combustion of fuel it is easier to move more mass at a slower speed than it is to move less mass at a higher speed hence the drive towards high bypass engines. This starts to not work so much at higher speeds when drag (function of velocity squared) and shocks (which are exasperated by the fact that large fan blades go supersonic before the aircraft does for turboprops) become real obstacles that necessitate lower bypass ratios.