"Some blogs, like TechCrunch and Mashable are so loaded with widgets that they take at least 30 seconds to fully render," gripes a post by frequent Valleywag commenter Alan Wilensky. So true! When I was a website producer, I used to plot page load times versus daily pageviews. Load speed affected traffic — and hence revenue and brand reach— far more than I could convince my managers.
The time it takes before the main text and/or images load matter, too, because most readers will start reading the page as soon as there's something to look at, rather than waiting for everything to settle into place. Dave Winer's Scripting News is a living lesson in speed over flash. I hit Dave's site once a day because I know it'll take under 10 seconds to load the page, scroll down it for Valleywag-grade dirt, and then move on to another site. Yet for whatever reason, I've never been able to personally convince anyone to lighten up a heavy front door. Oh, everyone who cares uses RSS now. Tech people have the best excuses for laziness.