LGTM to extend experimenting till M159 (inclusive). Thanks for pushing this!! :)
On Thu, Oct 8, 2026 at 8:04 AM Lingqi Chi <[email protected]> wrote: > Thank you for your comment! > We observed that using the existing prerender process model forces > same-origin navigations to create and use a new process, which introduces > unnecessary overhead. > To address this, we updated the process model to allow > prerender-until-script to reuse the initiator's renderer process (mimicking > normal same-origin navigation) to evaluate whether this improves > performance. > On Thursday, October 8, 2026 at 2:59:59 PM UTC+9 Yoav Weiss wrote: > >> Can you comment on the progress made towards shipping since the last >> experiment extension? >> >> On Wed, Oct 7, 2026 at 4:27 AM Chromestatus < >> [email protected]> wrote: >> >>> *Contact emails* >>> [email protected], [email protected] >>> >>> *Explainer* >>> >>> https://github.com/WICG/nav-speculation/blob/main/prerender-until-script.md >>> >>> *Specification* >>> >>> https://wicg.github.io/nav-speculation/prerendering.html#speculation-rule-set-prerender_until_script-rules >>> >>> *Design docs* >>> >>> >>> https://docs.google.com/document/d/18Ny-OJ5kfyxkZ8h73OGigk8B3gDnoxjH34RVcvSo5Do/edit?tab=t.szm4nrdsfrjv >>> >>> *Summary* >>> This extends speculation rules to introduce a new action called >>> prerender_until_script. It is designed as an intermediate option between >>> the existing prefetch (which only fetches the main document) and prerender >>> (which fully renders the page and runs all scripts). This new action will >>> fetch and parse a page, discover and download its subresources like images >>> and stylesheets, but will pause all script execution. When the user >>> navigates to the page, it activates, and all the deferred scripts are then >>> executed in order. This allows for a near-instant page load for >>> content-heavy sites without the performance cost or side effects of running >>> analytics or third-party scripts prematurely. >>> >>> *Blink component* >>> Internals>Preload>Prerender >>> <https://issues.chromium.org/issues?q=customfield1222907:%22Internals%3EPreload%3EPrerender%22> >>> >>> *Web Feature ID* >>> speculation-rules <https://webstatus.dev/features/speculation-rules> >>> >>> *Search tags* >>> speculationrules <http:///features#tags:speculationrules>, prerendering >>> <http:///features#tags:prerendering>, prefetch >>> <http:///features#tags:prefetch>, nostateprefetch >>> <http:///features#tags:nostateprefetch> >>> >>> *TAG review* >>> https://github.com/w3ctag/design-reviews/issues/1183 >>> >>> *TAG review status* >>> Not applicable >>> >>> *Origin Trial Name* >>> PrerenderUntilScript >>> >>> *Goals for experimentation* >>> - whether this feature work as expected on developers' sites. - whether >>> it is safe to leave inline event handlers as it is on websites. Developers >>> will be able to monitor the error rate of JavaScript execution, and provide >>> feedback on that. >>> >>> *Chromium Trial Name* >>> PrerenderUntilScript >>> >>> *Origin Trial documentation link* >>> >>> https://github.com/WICG/nav-speculation/blob/main/prerender-until-script.md >>> >>> *WebFeature UseCounter name* >>> kSpeculationRulesPrerenderUntilScript >>> >>> *Risks* >>> >>> >>> *Interoperability and Compatibility* >>> Other browsers do not implement this feature yet, but if should be safe >>> because: 1. it is an optimization, so it should be no-op on other browsers >>> 2. other browsers do not implement any of speculationrule actions yet. >>> >>> *Gecko*: No signal >>> >>> *WebKit*: No signal >>> >>> *Web developers*: Positive ( >>> https://github.com/WICG/nav-speculation/issues/305) Web developers >>> proposed that UA should implement an intermediate option between the >>> existing prefetch and prerender actions. >>> >>> *Other signals*: >>> >>> *Ergonomics* >>> no >>> >>> *Activation* >>> No. Developers should be able to easily try this feature by changing >>> "prerender" to "prerender_until_script" following the explainer. >>> >>> *Security* >>> It should be as safe as prerender action, as it pauses JavaScript >>> execution during prerendering. One potential risk is the inline event >>> handlers. inline event handlers will be executed normally during >>> prerendering, it seems risky but we find websites usually put inline >>> scripts before defining a inline event handler, and the inline script will >>> make the parser be paused, therefore user agent has no chance to execute >>> the inline event handlers. So, we think is is a low possibility risk, and >>> would like to confirm with Origin Trial. >>> >>> *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* >>> >>> >>> *Reason this experiment is being extended* >>> 1. Developers have reported that it is currently slower than prefetch. >>> We suspect one of the reasons is that the >>> Prerender2FallbackPrefetchSpecRules feature is not yet enabled by default. >>> Since this feature is launching soon, we'd like to monitor our metrics once >>> it goes live to see if performance improves. 2. Some developers says that >>> they do not have enough bandwidth to work on it and they're moving slowly, >>> so we'd like to extend the OT to wait for their feedback. >>> >>> *Reason this experiment is being extended* >>> We realized there might be a performance issue, and since the >>> optimization is included in M154, we would like to extend the OT to allow >>> partners to re-try this. >>> >>> *Ongoing technical constraints* >>> We assume it is ok not to handle inline event handlers differently as >>> for now most pages put <script> tag before inline event handlers. But if it >>> happens, we need to refine the inline event handlers' execution logic. >>> >>> *Debuggability* >>> As well as other speculationrule features, this feature shows its >>> current status on devtools. >>> >>> *Will this feature be supported on all six Blink platforms (Windows, >>> Mac, Linux, ChromeOS, Android, and Android WebView)?* >>> Yes >>> >>> *Is this feature fully tested by web-platform-tests >>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* >>> Yes >>> >>> >>> *Flag name on about://flags* >>> prerender-until-script >>> >>> *Finch feature name* >>> PrerenderUntilScript >>> >>> *Requires code in //chrome?* >>> False >>> >>> *Tracking bug* >>> https://issues.chromium.org/u/1/issues/428500219 >>> >>> *Measurement* >>> Blink.UseCounter.Features >>> >>> *Estimated milestones* >>> Origin trial desktop first 144 >>> Origin trial desktop last 150 >>> Origin trial extension 1 end milestone 154 >>> Origin trial extension 2 end milestone 159 >>> DevTrial on desktop 144 >>> Origin trial Android first 144 >>> Origin trial Android last 150 >>> DevTrial on Android 144 >>> Origin trial WebView first 144 >>> Origin trial WebView last 150 >>> >>> *Link to entry on the Chrome Platform Status* >>> https://chromestatus.com/feature/6324676351623168?gate=5423768481693696 >>> >>> *Links to previous Intent discussions* >>> Intent to Prototype: >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68f20f78.050a0220.29f70d.004e.GAE%40google.com >>> Intent to Experiment: >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6965e5e2.050a0220.22847.035a.GAE%40google.com >>> Intent to Extend Experiment 1: >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6a1e652b.c5ff9f8d.331a2d.02bd.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/6ac5ae1d.a448aa95.130ec9.016d.GAE%40google.com >>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6ac5ae1d.a448aa95.130ec9.016d.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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