Twitter allows you send 140 characters in a tweet, which (when you add entities, hashtags, and all that) ends up in the 4KB range as represented in the JSON API. 140 is what you see, so I’m going to go out on a limb and suggest that a single tweet page on Twitter has about a 15,000-to-one ratio of garbage to content.
I get links to tweets by mail, etc. on a regular basis, and the aggressive anti-performance and apparent contempt for the web by Twitter’s designers is probably the thing that gets me most irrationally riled-up on a daily basis. How does this pass design review? Who looks at a page this massive, this typically broken and says “go with it”?