ARM also decodes to uOps, and no that decoding is not a huge source of wasted power. The vast, vast majority of power (and thus heat) in x86 CPUs (or ARM for th

ARM also decodes to uOps, and no that decoding is not a huge source of wasted power. The vast, vast majority of power (and thus heat) in x86 CPUs (or ARM for that matter) is spent doing actual work. Ie, speculation, branch prediction, doing the actual ALU math, cache management, prefetching, etc... Almost none of it goes to dealing with the ISA. The almost singular advantage ARM has is just the looser memory model, although the best ARM CPU on the market by a landslide (Apple's M1) can run x86's memory model, and it seemingly doesn't cost much (hence how Rosetta 2 can perform so well)