There's 1,262,537 lines of elisp in 25.3, compared to 291,203 lines of C and C headers. While there is a fair amount of C code to do what you mentioned, much of the C is definitions for the core lisp language with 1,483 DEFUN statements in it.

But yah, not tiny, sure. I'm looking forward to it being replaced via the REmacs project.

https://github.com/Wilfred/remacs