Once you have added quite a few concerts to your profile, the stats for your Top Bands, Top Venues, and Top Locations don't get updated in real-time. Instead, the server updates them in batches behind the scenes once per hour. By doing it this way, the servers can stay speedy even if you have been to thousands of concerts.
If you see the "Recalculations Pending" message on your Overview page, that means that your Top Bands/Venues/Locations lists are still in the process of being recalculated. A recalculation happens after you add or remove a concert, mark a band as seen/not seen, etc.
Once your lists have been recalculated, the message will disappear.