Comment by ibdknox | Hacker News Reader

Comment by ibdknox | Hacker News Reader

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In terms of #3, if you're yielding until the next requestAnimationFrame, the browser is telling you when you have the opportunity to do more work. Is there something that isn't covered by that?

> they're already fast enough that most of the time is spent in rendering, not in javascript DOM manipulation

That hasn't been my experience, but it's been awhile since I've benchmarked any of the frameworks in common use. Change tracking, diffing, and then the dom calls have all been the bulk of the work in large updates. Assuming you're doing those in a dom fragment I'm not sure how "rendering time" (I'm taking that to mean compositing and painting?) could be the bottleneck in that scenario.

BTW if you're curious, browser DOM operations have advanced now to the point that doing work in dom fragments is often slower than just doing it right in the main tree. See, for instance, one of the recent optimizations to the vanillajs implementation of js-framework-benchmark: https://github.com/krausest/js-framework-benchmark/commit/2e...

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).

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