While FPU performance has historically been measured in gigaflops, some modern processors run over 1,000 FLOPS, which is why new measurements are often displayed in teraflops. A similar transition has taken place with clock speeds, which are no longer measured in megahertz, but in gigahertz. Teraflops are often used to measure supercomputer performance and the rate of scientific calculations, which are based primarily on floating point operations.