Lua has many different implementations and derived languages (among others, these include LuaJIT, TypedLua, Starlight, Ravi, Terra and Moonscript). In this talk we'll compare standard Lua with the popular LuaJIT, known especially for its speed. The topics covered include: an introduction to Lua and LuaJIT; compatibility and code styling differences; use cases; and issues you should be aware of.