Iron law of processor performance

In computer architecture, the iron law of processor performance (or simply iron law of performance) describes the performance trade-off between complexity and the number of primitive instructions that processors use to perform calculations. This formulation of the trade-off spurred the development of Reduced Instruction Set Computers (RISC) whose instruction set architectures (ISAs) leverage a smaller set of core instructions to improve performance. The term was coined by Douglas Clark based on research performed by Clark and Joel Emer in the 1980s.