Non-blocking for the experiment, but I think it'd be good to: * Expand on the use case you're trying to resolve. Do you want to reduce the amount of paints that are happening during the page load? Reduce the amount of scripts running as part of `requestAnimationFrame`? Something else?
It might also be worthwhile to talk with +Kouhei Ueno <kou...@chromium.org> and folks, as I know they are experimenting with an explicit signal to stop the HTML parser at some point during the page load, to see if it provides benefits. That may or may not be related to your goals here. On Fri, Jun 20, 2025 at 6:31 PM Mike Taylor <miketa...@chromium.org> wrote: > LGTM to experiment from M139 to M144 (inclusive). > On 6/15/25 11:04 p.m., 'Jiacheng Guo' via blink-dev wrote: > > Contact emails > > g...@google.com > > Explainer > > https://github.com/whatwg/html/issues/11070 > > Specification > > None > > Summary > > We propose to add a new render blocking token full-frame-rate to the > blocking attributes. When the renderer is blocked with the full-frame-rate > token, the renderer will work at a lower frame rate so as to reserve more > resources for loading. > > An example use case of the proposed API will be: > > The web page contains an element <link rel="expect" > href="#critical-content" blocking="full-frame-rate"/> in the page head. > After parsing this element, the renderer will work at an > implementation-specific lower frame rate. > > After the #critical-content element is parsed, the renderer will restore > its frame rate. > > It is worth noting that the frame rate instructions will be informative. > The browser may decide to lower the frame rate before parsing a blocking > element. For instance, the frame rate may be lowered at the very beginning > of the loading phase. On the other hand, the browser may also decide to > restore the frame rate before the frame rate blocking element list gets > empty. For instance, the frame rate may be restored after a timeout or > certain user interactions. > > > > Blink component > > Blink>Compositing > <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ECompositing%22> > > TAG review > > None > > TAG review status > > Pending > > We plan to run a quick test so as to verify the loading performance impact > on certain sites. Field experiments on the beta channel do not show > significant loading performance improvement so the feature may not be > shipped at all. Thus, we'll delay requesting TAG review and other browser > signals until we are more confident in the feature's value. > > Risks > > Interoperability and Compatibility > > None > > The API is introducing an informative signal to lower the frame rate > during loading. The browsers not implementing the feature will simply > ignore the element. The behavior will not change on these browsers. We > consider the risk to be minimal. > > Gecko: No signal > > WebKit: No signal > > Web developers: No signals > > Other signals: > > WebView application risks > > Does this intent deprecate or change behavior of existing APIs, such that > it has potentially high risk for Android WebView-based applications? > > None > > > Goals for experimentation > > We would like to verify the impact of the frame rate blocking API on the > loading performance. The loading performance changed will be measured by > the UMA WebVitals.FirstContentfulPaint4 and > WebVitals.LargestContentfulPaint3. The developers can also measure the > impact by collecting latency data in the page loading process. > > > > Ongoing technical constraints > > None > > > Debuggability > > None > > > Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, ChromeOS, Android, and Android WebView)? > > No > > Yes > Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> > ? > > No > > Acquiring the frame rate during page loading in javascript turned out to > be very difficult and the result is unpredictable on different platforms. > Thus it is hard to add a test to verify that the frame rate is really > lowered during loading in web tests. > > Flag name on about://flags > > None > > Finch feature name > > RenderBlockingFullFrameRate > > Requires code in //chrome? > > False > > Tracking bug > > https://crbug.com/397832388 > > Launch bug > > https://launch.corp.google.com/launch/4385256 > > Estimated milestones > > Origin trial desktop first > > 139 > > Origin trial desktop last > > 144 > > Origin trial Android first > > 139 > > Origin trial Android last > > 144 > > Origin trial WebView first > > 139 > > Origin trial WebView last > > 144 > > > Link to entry on the Chrome Platform Status > > https://chromestatus.com/feature/5207202081800192?gate=5073049818497024 > > Links to previous Intent discussions > > Intent to Prototype: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/67c7dfbb.2b0a0220.1efd8e.0902.GAE%40google.com > > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to blink-dev+unsubscr...@chromium.org. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAJQw1NxZLiK3FW6ny%2BYuyF%3D%3DJW7WFEeXsLoiOuzeoUXnk171Rg%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAJQw1NxZLiK3FW6ny%2BYuyF%3D%3DJW7WFEeXsLoiOuzeoUXnk171Rg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to blink-dev+unsubscr...@chromium.org. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/d123c2b6-bacb-4b21-bb45-425e7157ef38%40chromium.org > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/d123c2b6-bacb-4b21-bb45-425e7157ef38%40chromium.org?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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