I think Lua is catching a stray here. For most uses, Lua, even the PUC-Rio/vanilla implementation, is pretty fast. LuaJIT is quite fast. And because Lua is an embedded language authors can defer to C or whatever the host language is for bottlenecks requiring more speed. IDK if people are seeking dynamic types specifically, but it sure is nice to have stuff like memory management + easy string manipulation built-in sometimes.