> Firstly, the sleep and operating modes being as efficient as possible (the CPU design) My point is that this part doesn't really have much to do with the ins

> Firstly, the sleep and operating modes being as efficient as possible (the CPU design) My point is that this part doesn't really have much to do with the instruction set, though. Theoretically, there's no reason you couldn't design an x86 CPU that is just as efficient as an ARM one (or at least, within spitting distance); it's just not done because the economics wouldn't make sense.