The only thing I've found that LLM speeds up my work is a sort of advanced find replace.
A prompt like " I want to make this change in the code where any logic deals with XXX. To be/do XXX instead/additionally/somelogicchange/whatever"
It has been pretty decent at these types of changes and saves time of poking though and finding all the places I would have updated manually in a way that find/replace never could. Though I've never tried this on a huge code base.
I supposed you haven’t tried emacs grep mode or vim quickfix? If the change is mechanical, you create a macro and be done in seconds. If it’s not, you still got the high level overview and quick navigation.
> A prompt like " I want to make this change in the code where any logic deals with XXX. To be/do XXX instead/additionally/somelogicchange/whatever"
If I reached a point where I would find this helpful, I would take this as a sign that I have structured the code wrongly.