> It's worth noting that Emacs's built-in way to find files (project-find-file) in a project does not suffer these performance issues. Try it, C-x p f.
That is your personal key binding, project-find-file does not seem to have a default key binding. (This, by I which I mean telling people that some built-in command is bound to some key while forgetting that is in my configuration and not by default, has happened to me several times.)
Actually it's a default key binding in the (yet unreleased) Emacs 28. project.el has a lot of nice improvements in the upcoming version of Emacs. (I imagine the grandparent comment author just checked the version tag in `C-h k C-x p f' to see when it was released, but currently on Emacs HEAD the keybinding doesn't have a proper version tag - that's a big, albeit minor)
That is your personal key binding, project-find-file does not seem to have a default key binding. (This, by I which I mean telling people that some built-in command is bound to some key while forgetting that is in my configuration and not by default, has happened to me several times.)