The impression that Emacs and Emacs Lisp are heavyweight comes from the 1980s. (Since then Emacs Lisp has gained the ability to talk to GTK+ and to the GUI tool

The impression that Emacs and Emacs Lisp are heavyweight comes from the 1980s. (Since then Emacs Lisp has gained the ability to talk to GTK+ and to the GUI toolkits native to Mac and Windows, but has bloated up very little otherwise.) Compared to for example 2020's Firefox or Chrome, 2020's Emacs Lisp is very lightweight.