I have a 3y old 1.3GHz cpu with integrated graphics only on Gentoo, but it's so smooth, I can't believe it's not a video! How do they make it so smooth?

When I click the last page button on the right side, it runs smoothly through all animations, same when happens when I scroll around. Can't wait to see someone make a blog post on: "This is how Sony exploited HTML5 to run Smooth Parallax Effects on their Page".

I ran it in Firefox with about ~100 tabs open having over a dozen addons, an IDE opened and npm install running in the background.