Right now there are a lot of things that specs let you do that will make your page slow, like running a lot of js in the scroll event handler, or just including

Right now there are a lot of things that specs let you do that will make your page slow, like running a lot of js in the scroll event handler, or just including too much js overall. If you read the current proposal [1] the idea is that the site could make promises not to do various kinds of slow things, and the browser could enforce that. [1] http://wicg.github.io/ContentPerformancePolicy/ http://wicg.github.io/ContentPerformancePolicy/