Idea suggested by a reader: try to list not only the repositories with slowest code review, but also also the quickest (with more than N open changesets, or something along these lines).
Topic on Talk:Developer Relations/Weekly summary
I have started looking at this, but there is no evident parameter to reflect the quickest ones with the data we have today. The quickest are those with 0 open changesets... Still, I do see the point. I will keep thinking.
File an enhancement request in Phab? Though low prio; want to fix bugs instead of adding more features and "nice-to-have" metrics (though this one is a carrot and not a stick, yay).