The intent was to demonstrate how to write a module in C. This can be solved with Lua as well.

I was hoping for a performance related answer, but you are right. I might walk through this and see if one way is faster than the other. Thanks!

Using Lua is much easier. Performance is unlikely to be a bottleneck. Developing a module is a real pain and a last resort.

Using Lua is certainly easier. The C version will almost always be faster, and yes, performance in this scenario probably wouldn't be an issue between the two. The other reason for writing a module in C though is complete control over the execution and an easier time troubleshooting problems. Adding another language layer can present issues when things explode.