I guess they do? Eclipse itself is many millions of lines of code, and far as I can tell, it seems that the prescribed way to develop for it, is to use Eclipse

I guess they do? Eclipse itself is many millions of lines of code, and far as I can tell, it seems that the prescribed way to develop for it, is to use Eclipse itself. I mean, if you search for a string, Eclipse comes back quick because it indexed all your files. Run a grep? It comes back 6X slower (on my adhoc test)