It seams interesting to me that what we refer to as the conscious mind is unconscious a third of each day and the part we call unconscious is active 24 by 7.
First, I don't think the "unconscious" part is a single process, but myriad processes, and I'd bet they wax and wane.
Second, the "conscious" part is the part that can reason about itself and think abstractly. I think it would be correct to say it's doing higher level computations. The important part is that this is more costly - it's not optimized because it has to be flexible, so it would make sense that it's resting as often as possible.
Looks like ARM got it right with its big.LITTLE architecture. :)
And they stay in the brain even when not used. You can ride a bike or play a piano years after stopping.