I cleared out all the widget caches ((I’d added the new widget from Twitscoop. It’s in an iframe, and thus the executing Javascript inside doesn’t add to the load time of my page. That’s different from straight Javascript widgets, like Google Reader or the Twitter badge; the naked Javascript executes and blocks your page load. In other words, iframes rock with respect to this kind of thing—unless you need the generated HTML to match your theme, in which case, not so much.)) and reloaded the page to regenerate them all.

Total load time for the front page, all widgets, and also the WP Widget Cache writing them to disk:

86 queries. 1.314 seconds.

Total load time for the front page and just WP Widget Cache reading the widgets from disk (no individual widget cache has yet expired:

45 queries. 0.191 seconds.

The queries have pretty much been cut in half, and the load time cut down in much more than that. Sometimes the number of queries/load time increases a little, because some of the widgets have expired their cache and thus must be regenerated, but otherwise the page just loads quickly.

WP Widget Cache: made of win.