We rendered a million web pages to find out what makes the web slow

* Make as few requests as you can. Number of requests matters more than number of kilobytes transferred.

* For the request you have to make, do them over HTTP2 or greater if you can.

* Strive to avoid render blocking requests when you can, prefer async loading when possible.

Biggest slowdown source was iframes in onlod handlers. Would be interesting to see what those iframes were for, or at least what proportion are ads and trackers.