Database or cookies for marking forums?

[frozt]

I noticed that 3.5 has an option that tells the forum to use cookies or the database to track what forums a user has read. It says that using the database for marking these threads is indeed better, but alas more processor and memory intensive.

Now my question is, how much more intensive does this get? If it's not noticable on a relatively small board (something along the lines of 10k members) then I might as well turn it on. But if it bogs the site down even at a few hundred concurrent users, then I guess it's useless.

Are there any empiric figures on this, or should I simply just enable it and see what gives?

[Jake Bunce]

Hundreds of concurrent users is a lot. You may experience performance problems with database read marking on your forum. Just enable the option and see how your forum performs during peak hours.