Agreed--Go isn't in the top tier of languages with respect to efficiency--the languages in this tier trade off a lot of other facets to get high performance, and those tradeoffs don't align well with Go's goals. That said, I would be curious what sorts of optimizations Go could add which would pay for themselves with respect to keeping compile times fast. I don't know a lot about compiler optimizations, but I find the topic very interesting at least as it pertains to languages I use (I really don't care much about Haskell or OCaml or any of the other PLT darlings).