It might be truly that Lua is simpler but also keep in mind that LuaJIT was entirely created by a single person. So it can be done. And to quote Mike Pall aga

It might be truly that Lua is simpler but also keep in mind that LuaJIT was entirely created by a single person. So it can be done. And to quote Mike Pall again "" tl;dr: The reason why X is slow, is because X's implementation is slow, unoptimized or untuned. Language design just influences how hard it is to make up for it. There are no excuses. "