> I suspect this is related to asynch loading. The first query is still
> filling into the buffer, and emacs doesn't starting filling the second
> buffer until the first search finishes. In my experiments it
> _eventually_ does the second query.

You are correct. I confirm that the second query eventually gets
executed. 

> It just takes a while. I agree it would be nice if there was some UI
> hint before the first result arrives.

Yes, a simple update in the statusbar for the mode name would be a
possible approach.

  Sebastian