A high-performance CPU contains a lot of ancillary logic to achieve this performance (reorder buffers etc.). Moreover, the performance gain has super-linear power use.
Two smaller CPUs give twice the performance of a single smaller CPU at only twice the power.
This is the basis of ARM's big.LITTLE system where CPU state is shunted between different core designs as the measured load varies. »big.LITTLE Processing
|23: (C) 2008-13, DJ Greaves, University of Cambridge, Computer Laboratory.|