Looks like there's some lazy loading of later content so I actually get accessible content very quickly, indeed I thought something was up as the page appeared to be only a couple-hundred kB, which didn't match your description.
Scrolling down I continue (in FF Network Monitor) to see content loading - reviewing I see that YouTube is responsible for over 1MB of "base.js" which gets downloaded 7 times, and ¼MB of CSS files (again 7 times over). Now Atwood may be to blame in part but Google ... shouldn't they at least do better?? CodingHorror is loading very large image files [1] (which get scaled) for me, perhaps a "retina" handling issue.
Seems that images such as the superman image [0] or pinball image [1] currently on the front page are much much larger than they should be -- body max-width is 700 (70% of 1000px). Even for retina that's overkill. If you want to get really fancy you could restrict all (served) image widths to under 700px and make a 1400px @2x version to use in a srcset.
I'm working on a visually lossless optimization tool [1] and could reduce the images a bit further from 20.8MB to 16.11MB (-22.6%). But you're right, hidpi images is the main cost factor, adding an srcset polyfill would be a good measure.
I mean, I'm all for avoiding premature optimizations, but 23MB for one page is just... wow.
EDIT: As a sanity check, I just tried loading the CH home page from a cold cache myself. Total weight: 31.26MB. Yowch.