> Plus, there's no reason that starting a TUI program should be that slow.
There's no reason why it shouldn't. You seem to think that the interface obliges a program into a certain performance pattern. No such obligation exists. And Emacs isn't a TUI program, it only happens to have a terminal interface among many others.
> You seem to think that the interface obliges a program into a certain performance pattern.
I think all software (or at least, any text editor) regardless of interface type should launch instantly. But it's more unjustifiable with TUI programs.