LGTM to experiment 147 to 152, inclusive This is a long-awaited feature, and it was thoroughly discussed in the WebPerfWG
On Wed, Mar 18, 2026 at 12:14 PM Chromestatus < [email protected]> wrote: > *Contact emails* > [email protected] > > *Explainer* > https://github.com/WICG/container-timing > > *Specification* > https://WICG.github.io/container-timing > > *Design docs* > > https://github.com/WICG/container-timing > > *Summary* > The Container Timing API enables monitoring when annotated sections of the > DOM are displayed on screen and have finished their initial paint. A > developer will have the ability to mark subsections of the DOM with the > containertiming attribute (similar to elementtiming for the Element Timing > API) and receive performance entries when that section has been painted for > the first time. This API will allow developers to measure the timing of > various components in their pages. > > *Blink component* > Blink>PerformanceAPIs > <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EPerformanceAPIs%22> > > *Web Feature ID* > *No information provided* > > *Search tags* > performance <http:///features#tags:performance>, container > <http:///features#tags:container>, timing <http:///features#tags:timing> > > *TAG review* > https://github.com/w3ctag/design-reviews/issues/1034 > > *TAG review status* > Issues addressed > > *Goals for experimentation* > During this Origin Trial, we are primarily looking to gain insight into: > ## The attribute-based instrumentation model - Usage patterns of > `containertiming` - Frequency and purpose of `containertiming-ignore` - > Number of annotated elements per page ## PerformanceObserver integration - > Adoption of PerformanceObserver with container-timing - Whether developers > batch-observe or use targeted observation - Whether buffering behavior > meets developer expectations ## Entry shape and timing semantics - Whether > the exposed timing values align with developer expectations relative to LCP > and Element Timing - Whether additional metadata fields are needed - > Whether any fields appear unused or redundant ## Edge cases and ergonomics > - Nested containers - Dynamically inserted elements - Interaction with > visibility changes and layout shifts > > *Origin Trial documentation link* > > https://blogs.igalia.com/dape/2026/02/10/container-timing-measuring-web-components-performance > > *Risks* > > > *Interoperability and Compatibility* > *No information provided* > > *Gecko*: Positive ( > https://github.com/mozilla/standards-positions/issues/1155) Firefox are > positive and are working on an implementation: > https://phabricator.services.mozilla.com/D279373 > > *WebKit*: Neutral ( > https://github.com/WebKit/standards-positions/issues/442) > > *Web developers*: No signals > > *Other signals*: > > *Ergonomics* > Performance overhead only happens when enabling, any overhead is low > because we piggy back on DOM-traversals which are already happening. > > *Activation* > The feature is consistent with other Performance APIs that work on the > Performance Timeline. This feature can't be polyfilled properly, there has > been an attempt (see Explainer) but that has high resource usage. Today all > the documentation lives in the explainer, we will hope to promote this more > once it is exposed to the wider development community. > > *Security* > > https://github.com/WICG/container-timing/?tab=readme-ov-file#security-and-privacy > > *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? > *No information provided* > > > *Ongoing technical constraints* > None > > *Debuggability* > Container Timing entries can be printed to the developer console from the > PerformanceObserver. The attributes are also observable in the Elements > Panel. This feature has basic support from DevTools. > > *Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, ChromeOS, Android, and Android WebView)?* > Yes > This feature is implemented in Blink and isn't subject to any platform > specific APIs > > *Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* > Yes > > https://wpt.fyi/results/container-timing/tentative?label=experimental&label=master&aligned > > *DevTrial instructions* > > https://github.com/WICG/container-timing?tab=readme-ov-file#chrome-canary-and-chrome-beta > > *Flag name on about://flags* > enable-experimental-web-platform-features > > *Finch feature name* > ContainerTiming > > *Requires code in //chrome?* > False > > *Tracking bug* > https://issues.chromium.org/issues/382422286 > > *Measurement* > > https://chromestatus.com/metrics/feature/popularity#V8Element_ContainerTimingIgnore_AttributeGetter > https://chromestatus.com/metrics/feature/popularity#V8Element_ContainerTiming_AttributeGetter > https://chromestatus.com/metrics/feature/popularity#ContainerTimingObserverRegistered > > *Estimated milestones* > Origin trial desktop first 147 > Origin trial desktop last 152 > DevTrial on desktop 145 > Origin trial Android first 147 > Origin trial Android last 152 > DevTrial on Android 145 > Origin trial WebView first 147 > Origin trial WebView last 152 > > *Link to entry on the Chrome Platform Status* > https://chromestatus.com/feature/5110962817073152?gate=5112674898411520 > > *Links to previous Intent discussions* > Intent to Prototype: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/672cffcd.2b0a0220.d9f4a.0540.GAE%40google.com > > > This intent message was generated by Chrome Platform Status > <https://chromestatus.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 [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/69ba8919.050a0220.1bf526.0067.GAE%40google.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/69ba8919.050a0220.1bf526.0067.GAE%40google.com?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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