The author did have an interesting follow-up comment on hn: news.ycombinator.com/item?id=37137110

> We did notice on a less powerful machines the browser getting overwhelmed with the rate of new content (even though we're only streaming 10/s instead of the full 3.5k/s actually happening on the backend). I don't know if the poor performance in this context is due to Soapbox, the browser, or just the hardware.

Have you tested Soapbox with that much volume before? Doubt Spinster or Poast are putting that much load on it.