Importantly, the server serving up the main page may not be the same one serving up static assets. You hit the main page and it sends back 103s telling your bro

Importantly, the server serving up the main page may not be the same one serving up static assets. You hit the main page and it sends back 103s telling your browser to then download a bunch of stuff off of a CDN ASAP even while the main page is still being transferred.