If you want lighter and less rolling resistance, upgrade your tires. You know how much the wire beads weigh alone?

You're only going to find a significant reduction in rolling resistance if the hubs are incredibly bad, or the bearings were poorly installed or adjusted. If it's a cartridge bearing hub, then most of them roll about the same, unless the bearings were not pressed in properly. If it's a cup and cone hub, it probably came poorly adjusted from the factory and should be rebuilt.