"The likely cause is not one's computer, but is probably a fault of either the UBB.threads software or the server itself."
If that were the case then it would be more consistent across everyones computer. My guess would be an issue with dial up connections only?
I'm on a capped 512k cable connection which is relatively slow by todays standards and don't have any long thread problems.
I suspect it is a combination of speed and how people have their display preferences set.
I have mine set to:
default aged threads: show all threads
default sort order: descending date
default display mode: flat
default view: collapsed
parent posts to show per page: 10 (default)
total posts to show on one page: 100 (default)
For people on slow connections, they could lower the last entry.
When I view the forum, I see the number of new replies in the "Replies" column in red. If I click on that topic, it takes me to the new post. Since I am viewing in flat mode, it only has to render the number of posts as noted with "total posts to show on one page:".
With this setup, I don't see any reason that dial up people should be overly handicapped by large threads. You need not see the whole thread in order to see the new post(s).
-john