> the CPU could do the exact same thing for "mov eax, 0", couldn't it? Yes, it could, but mov eax, 0 is still going to also be six bytes of instruction in cach

> the CPU could do the exact same thing for "mov eax, 0", couldn't it? Yes, it could, but mov eax, 0 is still going to also be six bytes of instruction in cache, and fetched, and decoded, so optimizing on the shorter version is marginally better.