The UX mitigations section is interesting. The shifting of the layout after the first render is mitigated by CSS animations. That works when you have a "sparse" design like what they currently have. For sites with high density such as Hacker News, too many CSS animations happening after the first render could be a bad user experience.

I'm also wondering how to deal with scenario where we introduce sorting by popularity. With the current design, User might see articles swap places after the first render.