[pcwalton]

> People like to bash x86 but it has a big advantage: it's compact.

x86-64 isn't. I've measured this: the average instruction length is just about 4 bytes. REX prefixes add up quick.

[1amzave]

Is that really the definitive metric though? Seems like you'd want to compare overall program-text size between equivalent binaries for x86[-64] and $otherarch (i.e. x86 may be able to get away with fewer of those ~same-size instructions due to each of them doing slightly more on average).