[curveship]

If I understand what Glimmer is proposing, they want to slice a long update process into a set of batches, so that they can pause in the middle to let the browser render a frame. My points were that a) they don't know how long it will take the browser to render that frame, so it's hard to say when to cut off the batch, and b) rendering intermediate states might increase the overall work, sort of a classic throughput vs latency tradeoff.

Paint and composite are usually fast, but calculate styles, layout and hit test may not be. It totally depends on the complexity of the DOM and CSS, of course, but as an extreme example, the js-framework-benchmark tasks are often 90+% time in render. That's why the results converge on 1.00: 0.95 of that is time spent in the browser rendering the DOM, and the time spent in javascript between a framework at 1.00 and one at 1.05 may be 2x difference (0.05 vs 0.10).