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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