I'm seeing a range from snappy to several seconds (favoring snappy), so I'm going to guess "better caching."
Taking several seconds to load was common enough before that I would load the index & queue up all the articles I was interested in at once in new tabs, then grab my coffee. I may be able to just browse now, if this keeps up.
The JS is the largest delayer in here. Marked me 10s. But the page was loaded in 703ms. Sometimes, more. This can be even speed it up a lot by taking out the extra HTML/CSS used. By the quantity of CSS this site uses, better to include it in header than having it linked.
I've been using HN for many years and pages usually take more than a second or two to load, sometimes several. How long have you been using HN? Have we been using the same site and experiencing different load times?