I don't know that this is an accurate statement. The page for chat is static. Everything except the text coming in is downloaded once. If I'm reading through pages in the forum, I'm constantly requesting full page content including images and advertisements (both huge resource hogs) as well as all the html and script to run the page. I honestly think having a user participating in chat should be less resource intensive that someone reading through forums. Again, this is implementation dependent. If your chat is using more server resources than normal browsing, that's a red flag in regards to the implementation to me. Additionally, as IPv6 becomes the standard over the next couple of years, true multicast should further reduce those resources.
Originally Posted by Takeshi Miike
Most of the images associated with the forum are ad related, so they generate revenue. While this is a resource to be considered for the admin, for ownership consideration, the revenue generation negates the resources they take. From what I have seen of the chat, the refresh is fairly quick - that means connections open and closed constantly.
Of course, this is all conjecture on our parts. Without looking at the code and actual logs, we're just stabbing in the dark.
IPv6 is far, far from reaching enough deployment to reap any tangible benefits, and wouldn't be a consideration until it actually does.