In the case of a new forum section being added to a list of forum sections — which I would regularly only need to view — I could then add a table if it doesn't have a table for that section.
Well, I for one would *NOT* add a new table just because a new forum section is added. Why? If you have a "ForumSections" table then all you have to do is add a new record to that to add a new forum section. No reason to create an entire table.
But in any case, I would think that adding a forum section--however it is done--would be the responsibility of and only allowed to be done by an administrator. And presumably it would be done via some admin-only web page. And then, again, that page needs the admin connection whereas normal pages need only a users connection. So, again, the entire page uses the same connection and there's no issue with closing a connection and opening another.
HOWEVER... Even if you did decide you needed to close the users connection and open the admin connection, that operation would presumably only be done very rarely and so who cares if you waste a few milliseconds a handful of times per day?