I want to assume this is tongue-in-cheek.. but I'm not actually sure?
The whole page. The text is available almost immediately, so not tongue-in-cheek. Who the fuck leaves a page that they went to if the see text and a page don't see all the pictures in 2 seconds? We have a shorter attention span but not that short.
I meant your comment. I think I have my answer.
Yes, it is. The popularly cited studies these days suggest an upper limit of one second to ensure a user maintains flow.
And consistent <250ms will feel like magic — try pinboard as an example of lightning fast UI
Pinboard doesn't have near the traffic or complexity as goodreads. It's basically fetching text out of a database with a user-id lookup. No multiple databases for books, user profile, reviews, etc.