As extension languages go, Lua is like a better Javascript. The whole design is cleaner, and it has a very high performance JIT compiler (LuaJIT, http://luajit.

As extension languages go, Lua is like a better Javascript. The whole design is cleaner, and it has a very high performance JIT compiler (LuaJIT, http://luajit.org/ http://luajit.org/) for x86 platforms. Mainly, though, I think the devs just prefer it. (I do, too.) Also, using a separate scripting language makes the local / web barrier clearer, which probably helps with security.