This is just a explanation of how I and quite a few others use the site daily and are able to keep up on posts...
FIRST: The "bookmark" or "favorite" that I use to get to the site points to the
forum index
SECOND: Once I am on the
forum index, to check new posts I simply click the X unread posts button by my name. SEE SCREENSHOT
That page will show you all the new posts that you have not read since your last visit.
OTHER STUFF:
Let's say you login after being away a long time and you have 8,432 post unread, you can't possibly catch up, you can go the quicklinks

menu (up top ^^) and click "mark forums read" that will set you back down to 0 unread posts.
If you want to mark just one particular forum as read, double-click on it's marker till it turns to the duller color, this thing on the forum index