2ACES

All tests were done on WPengine (which uses a custom varnish implementation, I think) with and without Cloudflare. I guess their cache keeps the headers sent by the original PHP...

### TL;DR - That's the approach we use on our production sites and apps. It should work with AO. - check both specifications drafts for [preload](https://www.w3.org/TR/preload/) and other [resource hints](https://www.w3.org/TR/resource-hints/)...

@zytzagoo interesting article indeed

Just to give some sanity check, we are not talking about only HTTP2 push header anymore, right? If so, maybe we should change the Issue title and description.

1. we gotta evaluate which resources to support; 2. we gotta evaluate which methods will be available (link element, http2 push); 3. decide if we use WordPress 4.6 class or...

About using WordPress class: it doesn't support preload right now. I think the best course of action would be expanding it for preload and HTTP2 push headers and if works...

@vijayaraghavanramanan : "for browsers which do not support preload, polyfill it with Autoptimize's existing js." My understanding of preload draft specification and for all tests I conducted is that pushing...

Just pinging here to 1 - apologize for not being active in the discussion/development because of health and other issues 2- fantastic collaboration in this post/feature, guys.