It's not so much the tread pattern, as the weight and materials of those tires.

Tread pattern is really pretty irrelevant on a road bike; i.e. it doesn't increase adhesion, and within limits, its not going to make much difference in rolling resistance.

The tires you've got are heavy, and have high rolling resistance. A good "racing" tire is going to be faster than those, regardless of whether it is one with a tread pattern, Vittorias for example, or slick, Michelin for example.