You could lose one with the avatar code, if you do some searching theres some nifty feature to get it without any extra work
Further more, you should not really run the ammount of new posts and threads on EVERY PAGELOAD, thats alot of overhead, for a small bit of information, also, without indecies on the tables, its going to be rather intensive in the long run.
You could Cache the ammount of newly registered users today and the ammount of users visiting online in some sort of datacache