How is the comon feature of marking threads in a forum achived. I have been writing my own forum for a while and so far all i can think of is a database but that would put a lot of strain on the database.
Comonly it will display a diffrent folder icon depending on what interaction that user has had with the forum, this would make my forum much more engaging for the end user but i really don't know how to achive this in a sensible manner.
