If AMP have shown us anything it is that Perf Matters™ and guaranteed performance matters even more.
Too many mobile sites are too slow, not due to lack of developers trying to make them faster, but because developers often have little control over third parties and page components that are managed by other teams. AMP is a framework that guarantees that a site will be performant, by limiting what it can do to avoid anti-patterns.
I believe we need a standard alternative to provide similar performance guaranties. We need to allow performance-conscious developers to opt-in to the browser's "fast-path", and to self-impose interventions in order to avoid performance anti-patterns on their site.
A very early draft of that concept can be found on http://yoavweiss.github.io/ContentPerformancePolicy/#introduction.
@tkadlec wrote about the thinking behind the proposal.
It's still very early stage, but if there's interest, I'd be happy to move the repo to the WICG org, and continue work on it here.