Ask HN: Why and how is Hacker News so fast?

I'm currently using an artificially-shaped 256k Internet connection (it resets in a couple days), and over the past few weeks browsing the web, I've very consistently found HN to be one of the fastest loading sites I've come across.

I understand that HN is built on top of Arc (http://arclanguage.org), a Lisp variant, and that the code (https://github.com/wting/hackernews/blob/master/news.arc) uses flat files to store post and vote data. This is generally speaking quite an unusual/unexpected architecture for a site presumed to serve a consistently moderate load, but HN manages to do so remarkably well, presumably because the site itself is so incredibly lightweight. I don't think the minimal HTML is the only factor though, although it probably counts for the majority.

I'm interested to understand as much as possible/practicable/relevant about the server(s') configuration, uplink bandwidth, other tunables, etc, so I can get an idea of what makes HN so exceptionally responsive and "a cut above 99% of everything else". Does CloudFlare really make that much of a difference? :P

I know there's some "secret sauce" in there somewhere, because virtually-verbatim clones of HN such as http://firespotting.com/ seem almost as fast... but just not as instantaneous as HN.

(PS: On the occasions I get hit by it, my ISP's shaping config seems quite involved/nuanced, and I actually want to profile it because it's so catalyzing and would be very useful to apply to my own projects for "worst-case" testing. For the interested, the details I have thus far can be found here: http://serverfault.com/questions/709529/how-can-i-profile-my-isps-bandwidth-shaping-settings)

Server-side is a different beast than the whole server->client part.

HN does not load particularly fast for me, 300-500ms is fairly slow.

Loading this webpage I downloaded ~12KB. For comparison, I went to the NYT homepage and downloaded ~1.2 MB. For people with shitty downlinks like you and I, the absence of exorbitant quantities of Javascript and images makes a lot of difference - a lot more than time-to-first-byte.

I haven't done any real analysis of it, but I've always assumed it's because it renders up a single small HTML document rather than large core content and dozens of external references (ads, analysis, etc.).

Looking at this page in my browser's network analyzer, I see a request for the page itself (3.8k), followed by requests for the css and a few images which don't impact layout. On top of that, JS isn't used for layout, so the HTML renderer can do its job.

Speed isn't everything. Hacker News has been recently one of the most unreliable website I frequent.