The reason it's difficult to make elisp fast is because the language defaults to dynamic scoping rather than lexical scoping. That means any function that uses `let` is no longer making a tailcall. Meaning you have to restore the value of each variable after you call whatever function would have been the tailcall.
Stuff like that adds up. It's why Lua is so fast compared to JS, too.
Stuff like that adds up. It's why Lua is so fast compared to JS, too.