I have to agree with @develcuy here.
LuaJIT implements some of the most cutting edge state-of-the-art JIT tracing techniques out there. I got around to benchmarking it against other scripting languages, like Python, Javascript(Node.js), Ruby in addition to some statically compiled languages like C, C++ and Java. I was surprised by the results, it was beating pretty much all of them except C and C++ -- yes, it was even beating V8 engine in NodeJS!
This is especially impressive when you consider LuaJIT is mostly the work of one man, my hats off to Mike Pall.
If you haven't considered Lua before, I definitely recommend checking LuaJIT. It has a nice C API interface that's much easier to work with(compare that to Python's C API). It's not just a scripting language, it works quite well as a general purpose language too.