On Tue, Mar 19, 2019 at 2:13 AM Xidorn Quan <m...@upsuper.org> wrote:
> On Tue, Mar 19, 2019, at 6:01 AM, Daniel Holbert wrote: > > As of today (March 18th 2019), I intend to turn CSS Containment > > <https://drafts.csswg.org/css-contain/> on by default on all platforms, > in > > Firefox Nightly 68. It has been developed behind the > > 'layout.css.contain.enabled' preference. > > IIRC this feature is designed to allow authors to provide hints to UAs for > some optimization opportunities in the rendering pipeline. > Right, yeah - that's the primary intent. Does our implementation also include any such optimizations for faster > rendering, or is it currently just a basic implementation for conformance? > It does! The main one is https://bugzilla.mozilla.org/show_bug.cgi?id=1497414 (making `contain:layout size` elements reflow roots. If we already include optimizations based on the hints, do we know how much > they help the performance? > It entirely depends on the use-case, and of course it depends on web authors opting in to use it. The best results will come from adding containment around rapidly-changing (i.e. frequently-reflowing) content, in a page with other expensive-to-reflow content (which we can then ignore during the frequent reflows, if we make the rapidly-changing area into a reflow root). As one example, we tried adding "contain:layout style" to the Web Console text-entry area in https://bugzilla.mozilla.org/show_bug.cgi?id=1502524 , and this gave a ~50% reduction in time spent in reflow for a particular stress test. However, we had to back it out in that case, because the Web Console's functionality depends on some layout information *not* being contained. But that's an example of the sort of speedup that this can give, in cases where it *is* appropriate to use. - Xidorn > _______________________________________________ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform > _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
