Unless you ride on glassy smooth roads (or steel rails) there is no rolling resistance to be lost by overinflating your tires. In fact, the ability of the tire casing to deform as it rolls over imperfect surfaces reduces rolling resistance as it increases traction and comfort. Think about it--a hard tire bounces and and gets pushed back by everything it hits, while a properly inflated tire deflects enough to roll over it. Oops, Froze beat me to it, while I was eating dinner. With a reference, no less. Good post, man.
For that reason, you should consider where you'll be riding while inflating your tires--chipseal or gravel, back off a few psi.
On the other hand, there are guys who will mount the widest tires they can fit on their bikes, and inflate them to where they're barely avoiding pinch flats or rolling the tire off the rim going around a corner, 65-70 psi. I don't see the point.