'subscribed threads to display'
I dont know about other users, but the only reason I find myself in my control panel 90% of the time is to see if there has been any reply to any of my subscribed threads. Often, there is not. It would definitely save me some time (and clicking) if there was a 'subscribed thread new posts' counter... A good place for it would be under the 'private messages' counter by your login info.
From a practical point of view, the tradeoff would seem to save bandwidth but add to the database queries.
Just a thought.