After a short period of inactivity (ie. reading through a long thread), the forum thinks you've logged out. This basically means that if you spend 10 minutes without refreshing or clicking links, all messages will be marked as read. Could it be easily modified to, say, 30 minutes before the forum decides that you're no longer visiting the site?

Hmm, I open the Show new posts since last visit and middle-click (open in new tab) all the new topics.

We can however change it, I think it's 600seconds now