"Yang writes that Facebook has been internally debating whether the page should display everything as quickly as possible, even before some necessary scripts to actually interact with the site have loaded, or to show a white page until everything is good to go and then render it all at once. Yang writes, “In all groups of users, keeping the page blank resulted in lower usage statistics. Thus the debate was resolved.” So if you’re ever on Facebook and you find that a certain button isn’t working for the first second or two after a page loads, this would explain it."

A Look Behind The Curtain At Facebook’s Optimization Efforts