At first I thought it was just my computer (a 2008 MacBook), but I just tried on a brand new i7 iMac and it takes forever to respond to scrolling. I'll try to scroll down the page and it will crawl, sputter, and jump all over the place.<p>9to5Mac is another culprit.<p>Do you have this problem? What other sites does your computer struggle with? What causes it?
Search Google for "Steve Souders" and read some of his articles. He is the foremost expert on front-end optimization (and is the guru behind such things as Google's async-loading analytics code).<p>The main problem with the sites that you mention isn't the number of widgets/elements that they load, but how and where they load them. If you want to know more about this, though, you should probably read the relevant threads on StackOverflow.