Can you elaborate on that?
Yes.
The drag produced by the side-slip increases as the square of the airspeed, so the increase in drag should more than compensate for the increase in groundspeed, which may be less than you at first imagine, due to the angle of descent. To illustrate this, think about a vertical descent. You can increase the airspeed as much as you like without increasing the groundspeed at all.
MJ
