The ironic thing is I'd hazard a guess (i'm not heavily into computers, but...) that the time-out threshold helps protect this site from spambots. In another forum of which I'm a member (it has nothing to do with sex, it's for internal discussion at a movie club) there are about 60 active members who help keep the club's business going (though the number who come to see films is higher) and a few earlier active members posting. The forum, however, has 1500 regged members, most of which of course are spambots posing as real people. Our webmaster keeps most of them from posting but it's kind of strange to have that long a list (he's been thinking lately of doing a clean-up of the list).

I haven't received a single spam/ad mail which could be traced to my membership on the BDSM forum, and that's very nice.

For me the time-out is around 10-15 minutes if I don't load a new page or refresh the page I'm on. The easy way to control it is to load a new page every few minutes (let's say you'll shift back and forth from a subforum to a specific thread every 8-10 minutes). All web browsers have the option of opening a new window which will at first hold the same page, so then you can simply keep one window at rest and move the other one about in the threads of the forum, to stay in and browse around what's happening.