I've commited my improvements to the list builder's pagination code.
Essentially I've sped it up by creating a separate paginator instance for each PAGE GROUP rather than one for the ENTIRE LIST.
This means that on openacs.org's Q&A forum, rather than filling a cache of 5500 entries whenever the cache is flushed, we're only filling 330, using LIMIT+OFFSET/ROWNUM tricks.
We then get the benefit of having cached the keys for the current page group until there's another post in the case of forums (not all clients of the list builder enable caching, of course).
I've also gotten rid of the Tcl-based sorting of the keys returned for use in the page display query's IN (keys) clause, a minor speedup.
There's probably still a lot of room for improvement, i.e. I can make lighter-weight list builder specific code to execute and cache the pagination query, etc. I'll poke at it periodically.
Currently the OpenACS Q&A forum takes about 1.6 seconds to display if the cache is flushed. It took about 18 seconds using the existing list builder. When the cache is available it takes about 750 milliseconds. Much of that seems to be running the listtemplate tag as the shorter the number of rows, the faster it goes.
Notice that performance of this can be impacted by changing the number of rows per page, and page groups per navigation widget, so I'll probably add these as parameters to forums at some point. You get quicker page displays by shrinking those numbers.
And of course I haven't added the performance improvements to forums itself that I have in mind ... those will help, too.
