High rolling resistance for sure - I average about 12 km/h (7.5 mph) on the studded tires in the winter. Running c. 9 p.s.i.
I'm running 4.8" up front, and 4.0" in the back.
Some years ago I rode Jr's single-speed 29er (2.1") on pavement to break in the studs (as recommended) and could really move on it. Of course it would be slower on snow and ice.
I average about 50% faster on my old 3-season Rocky Mountain mountain bike with 26" x 1.75" tires (18 kph vs 12 kph), but of course some of that difference is due to dry roads vs. ice and snow.