I have never heard that a cisc chip was more efficent than a risc chip.
It boils down to the most common operations that a processor executes. If
you can do the same process with fewer instructions, this translates to
fewer processor cycles per process so it is more efficent.  Intel just
decided to do the hotrod method.  To overcome the inefficent nature of our
cisc instruction set one can either soup up that chevy nova with a 435 hp
engine  Moterola with it's risc chips took the bmw approach. Lets
redesign the whole car, or design a new one that is lighter, more
aerodynamic so it needs a smaller more efficent engine. Thats why we have
1.7 ghz intels and 600mhz motorolas.  Pardon the spelling, I'm a bit
drunk.

Colin