In this video I demonstrate two built-in tools for navigating large files in a manner that is both efficient and convenient.

outline-minor-mode can be combined with a major mode for programming, such as emacs-lisp-mode, to produce headings that may then be expanded or contracted (same idea as with Org mode).
imenu presents a dynamically-generated index with points of interest in the given buffer (e.g. headings), allowing you to jump to one using completion methods.

Both tools are complemented by other packages as well as my own functions and minor extras.

Check my dotemacs for all the code and relevant documentation.