I was wondering if it is difficult to move the submenu of forum and members and move it to the username popup window, since is the same thing regardless of logged in or not, I would like to save the space.
You do realise that it this can be done (and I'm not sure it is wise as those submenus are applicable to specific tabs) that the username popup window will be too big to fit on the screen of a mobike phone? The current size takes up much of the screen already.
If done correctly the links removed from the subnav can be moved into each tab as a popup menu. There are styles out there that have options to do this which could save you the headache of doing it plus keeping it updated.