No, ground effect is (AFAIK) when the depth of the wing (fore-aft) is greater than the distance above the surface it is flying over. The leading edge of the wing creates a pressure wave that reflects back from the surface and provides lift to the whole wing. You can see it with birds like pelicans which skim the water for a long way without needing to flap at all. I don't know if this would enhance the speed at all though, there are presumably other effects involved with going faster.