Funny you say that, because I used my game engine to write a simple 3d shooter, and everything is implemented in Lua with the luaglut binding. I certianly wouldn't argue with your assertion that Lua is slower than a compiled language, but writing a 3D game engine in Lua isn't that bad of an idea. At least in my experience, the framerate of a game is influenced most by the geometry it is trying to render, not by the language in which it was written. For example, my engine's framerate doesn't improve at all when I use LuaJIT, because in reality there isn't much Lua code being interpretted each frame.
