Seems like LuaJIT could offer a "drop-in" performance boost for mod_lua .. ?
http://luajit.org/performance_x86.html
"LuaJIT is API-compatible with Lua 5.1. If you've already embedded Lua into
your application, you probably don't need to do anything to switch to
LuaJIT, except link with a different library ..."
http://luajit.org/install.html#embed
Regards,
JT