I'm new to Lua and I'm wondering, is it efficient to use Lua to store game data (such as monster's description, spells).

My problem is this: when I try to create a monster object every second, I have to run the Lua file and get the data repeatedly, which I think may be not efficient.

Before I try to use Lua, I use XML to store data: at the beginning of gameplay, I read the "monster.xml" file once, and keep it in the memory, and every time I need to create a monster, I just refer to it.

Is this XML approach more efficient than the Lua one ? Or are there other better solutions?