To be precise, we do two things different now:
(1) Check if the sender of a message is the same as the current user, in which case we skip messages coming from Pusher.
(2) Before sending msg data to Pusher, we copy-paste the html onto the message thread.
That's not really "writing code", as far as thousands of lines of code are concerned.
Ok that was large publisher with some truly crufty platforms but sill sub 1s page loads are probably the exception.
The nav bar and structure of the FB news feed shows up < 1s for me right now, but the actual contents of the page take another few seconds. Total 3 – 5 seconds for the browser to indicate it's fully loaded.
I've talked to some friends who work at FB and yeah, they use a lot of sequential loading (forgot the technical term for that). I wish I could implement more as well; someday.