Keeping up with a busy forum like this one could be a full-time job! Remember, no one expects you to read all of the threads in every folder.
If there is a particular folder (aka section of the forum) that you're not interested in, you can mark all messages in that folder as read very easily, by doing the following:
Note: If you click the black circle by accident, there's no way to undo it.
You can also mark an entire section or folder as read from the list of threads.
When you've read everything you're interested in, simply click the “Mark this forum read” button at the top of the page, just below the “Post Reply” button.
This will mark all messages in the current section or folder as read.