Then i vote for LuaJIT, hope you add it as soon as possible.

I'm working on integrating it as a dependency into my CMake build system version of Maratis. However, I haven't yet figured out how to build it properly except using the Makefiles included in LuaJIT.

LuaJIT is probably the fastest dynamic langage (the same lua we have now but with a Just-In-Time compiler).
There is plan to add it instead of the standard lua interpreter.