Insulating the hose has nothing to do with how many CFM of air the fan can move. It's the speed and and size of the fan blades. There's nothing you can do to make it run faster or push more air. If it's sized wrong then your going to have to add another one or replace the one you have.
The insulation is to stop the moisture inside the hose from condensing and runing back into the room or laying in the hose.