I have run into an issue that I can't use cookie based threadmarking since I have a website that has groups, and each group has a forum. This means that, potentially, a user could have more than 20 cookies to track 20 group forums.

20 cookies is the maximum allowed according to the HTTP spec. Above all, it would slow down access to the site as the cookie size adds up fast (1kb per threadmarking cookie => 20kb)

Now, I was wondering if db based threadmarking is sustainable? Who is using this on a large scale? Is sitepoint? I checked the cookies and I didn't see threadmarking cookies, so I guess so? What's the best timeout for threadmarking? 10 days is the default.

Thanks