change behaviour of "unread posts" on index page

[Bloodsurfer]

Would it be possible for someone to create a mod to change the default behaviour of SMF?

I'd like to have it marking unread posts in every subforum on the index page with database read tracking - the same way it is handled with the topics in every subforum, not with cookies as it is handled now.
I want the unread mark to stay, until there are no unread topics anymore. As it is now, the mark vanishes once you leave the subforum, wether there are further unread posts or not.

I know that it has an impact on performance. But my forum doesn't have too many users, and the performance is quite good. I wouldn't mind if it would take 0,25 seconds to load the index page instead of 0,07 seconds if you know what I mean.

I can't write such a mod by myself, don't have enough knowledge of php

[bebo94]

I could use the mod as well.