Lua's other strong point here is that it has an especially nice C API. Unlike Perl, Python, and Ruby, it was written primarily to script C, with use as a standalone language being secondary.

I prefer Lua to all of those, but that again is a matter of taste.

And yes, Lua is pretty fast, and LuaJIT (http://luajit.org/) is so fast that it's a major outlier among scripting languages.