Re: plugin idea: single page threads broken up by a divider…
Typically the cost of doing a query at all is the biggest performance concern, unless the query returns many thousands of records, then the size becomes a concern. It’s really all about profiling your code to see where the performance problems lie.
The problem here is that ajax doesn’t load large amounts of data very quickly… it’s best for small requests, not loading a giant page. There are many sites that use this technique, however, including sites like Digg.
Pre-fetching everything and hiding them has other concerns, because it would make every page load huge, and potentially without reason.