Io and Lua are light and embeddable but while Io is much slower than Go (and much higher level), I suspect Lua is probably the fastest scripting language around and LuaJIT may be competitive (perhaps even faster) than lower level garbage collected systems languages like Go and Java.
I've actually went to the Wikipedia to look up, who the creator of Io was. :)
No, seriously, thank you for creating it. Although I hadn't had the chance to use it in production (most of my stuff is just numerical), Io is an incredibly enlightening language.
Looking back, I wish I had written Io in Lua.