It's all perceived performances, not real, raw performances. Synchronous react rendering will still be as slow as ever. This rewrite is a bit pointless to me,

It's all perceived performances, not real, raw performances. Synchronous react rendering will still be as slow as ever. This rewrite is a bit pointless to me, increase the complexity of using React on the long term (before, you could count on synchronous rendering having predictive results) and is just a hack to spread the cost of react's rendering across multiple frames. If anything your site will take longer to render now that it's async :) I'm wary of progressively rendered sites (like Facebook) where buttons are rendered but don't work for the first few hundred milliseconds or seconds anyway. Complex websites can already defer the rendering of their most expensive parts (e.g google maps, etc); baking it in the framework sounds like engineers who had too much free time to me :p