Originally Posted by
Escape Path
The difference (savings) come from starting descent earlier (i.e. setting thrust to idle earlier) in a low speed descent. Since for a higher speed descent your calculated TOD will be further away than for a low speed one, you'll have cruise power for some minutes longer.
Just to clarify for anyone who may have had the same misreading as me initially, that's further away from the airplane before the decent starts, not further away from the airport