LGTM2
On 10/27/26 6:51 p.m., Alex Russell wrote:
Thanks for the data. It's exciting to hear about such a large
performance improvement.
LGTM1
Not blocking, but just curious: it would be unfortunate if the major
customers of this API were ad systems. Do we have good data from
non-ads use-cases?
Best,
Alex
On Wednesday, October 21, 2026 at 6:53:04 PM UTC-7 Yoichi Osato wrote:
> This Intent mentions an OT; was there feedback from developers
about the utility of x-origin iframe pre-rendering?
Yes, one of our customers shows significant performance
improvement(68%!) on speculative loading with this feature.
> Did we learn anything about the potential risks (e.g., to
metrics and privacy)?
No report from OT attendees so far.
2026年10月22日(木) 0:24 Alex Russell <[email protected]>:
Do we have a sense for which sorts of applications will
benefit from this change? This Intent mentions an OT; was
there feedback from developers about the utility of x-origin
iframe pre-rendering? Did we learn anything about the
potential risks (e.g., to metrics and privacy)?
Thanks,
Alex
On Wednesday, October 14, 2026 at 11:28:21 PM UTC-7
Chromestatus wrote:
*Contact emails*
[email protected]
*Explainer*
https://github.com/WICG/nav-speculation/blob/main/prerendering-cross-origin-iframes.md
<https://github.com/WICG/nav-speculation/blob/main/prerendering-cross-origin-iframes.md>
*Specification*
https://wicg.github.io/nav-speculation/prerendering.html
<https://wicg.github.io/nav-speculation/prerendering.html>
*Summary*
Prerenders cross-origin iframes with an opt-in response
header. Browsers will now prerender all cross-origin
frames if the top-level frame's HTTP response includes the
Supports-Loading-Mode: prerender-cross-origin-frames.
*Blink component*
Blink
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%22>
*Web Feature ID*
speculation-rules
<https://webstatus.dev/features/speculation-rules>
*Motivation*
By default, navigational prerendering delays the loading
of all cross-origin iframes until the referring page
activates the prerendered page. However, there are some
cases where cross-origin iframes are particularly
important to an application, such that delaying them
negates many of the benefits of prerendering.
*Initial public proposal*
https://groups.google.com/a/chromium.org/g/blink-dev/c/KP1f2UTqCgM/m/q_EQ5ceXHgAJ
<https://groups.google.com/a/chromium.org/g/blink-dev/c/KP1f2UTqCgM/m/q_EQ5ceXHgAJ>
*TAG review*
https://github.com/w3ctag/design-reviews/issues/1207
<https://github.com/w3ctag/design-reviews/issues/1207>
*TAG review status*
Issues addressed
*Origin Trial Name*
Prerendering cross-origin iframes
*Goals for experimentation*
Gather feedback from web authors who already are
interested in this feature.
*Chromium Trial Name*
Prerender2CrossOriginIframes
*Origin Trial documentation link*
https://github.com/WICG/nav-speculation/blob/main/prerendering-cross-origin-iframes.md
<https://github.com/WICG/nav-speculation/blob/main/prerendering-cross-origin-iframes.md>
*WebFeature UseCounter name*
kPrerender2CrossOriginIframes
*Risks*
*Interoperability and Compatibility*
The entire speculative loading feature is a progressive
enhancement, so in general risks are low in this area.
/Gecko/: No
signal (https://github.com/mozilla/standards-positions/issues/1376
<https://github.com/mozilla/standards-positions/issues/1376>) No
signal as of 2026-10-15
/WebKit/: No
signal (https://github.com/WebKit/standards-positions/issues/636
<https://github.com/WebKit/standards-positions/issues/636>) No
signal as of 2026-10-15
/Web developers/: Positive Our partners have given
positive feedback on this feature.
/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?
No.
*Debuggability*
The cross-origin iframe prerendering should be debuggable
as well as top frame's one:
https://developer.chrome.com/docs/devtools/application/debugging-speculation-rules#prerender
<https://developer.chrome.com/docs/devtools/application/debugging-speculation-rules#prerender>
*Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, ChromeOS, Android, and Android
WebView)?*
No
*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*
"prerender2-cross-origin-iframes" from M148
*Finch feature name*
Prerender2CrossOriginIframes
*Rollout plan*
Will ship enabled for all users
*Requires code in //chrome?*
False
*Tracking bug*
https://issues.chromium.org/issues/440387014
<https://issues.chromium.org/issues/440387014>
*Availability expectation*
Feature is available only in Chromium browsers for the
foreseeable future.
*Adoption expectation*
Feature is used by specific partner(s) to provide
functionality within 12 months of launch in Chrome.
*Adoption plan*
One of our partners has already joined in origin trial in
Chrome and shows better performance result.
*Non-OSS dependencies*
Does the feature depend on any code or APIs outside the
Chromium open source repository and its open-source
dependencies to function?
No.
*Estimated milestones*
Shipping on desktop 158
Origin trial desktop first 147
Origin trial desktop last 152
Origin trial extension 1 end milestone 158
Shipping on Android 158
Shipping on WebView 158
Shipping on iOS 158
*Anticipated spec changes*
Open questions about a feature may be a source of future
web compat or interop issues. Please list open issues
(e.g. links to known github issues in the project for the
feature specification) whose resolution may introduce web
compat/interop risk (e.g., changing to naming or structure
of the API in a non-backward-compatible way).
/No information provided/
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5112398709129216?gate=5121426126405632
<https://chromestatus.com/feature/5112398709129216?gate=5121426126405632>
*Links to previous Intent discussions*
Intent to Prototype:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68b670ba.050a0220.270bc4.0593.GAE%40google.com
<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68b670ba.050a0220.270bc4.0593.GAE%40google.com>
Intent to Experiment:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAAEV3p%3DzhNhfOpe8x%3DRKgxYFS9GCq_q-c8knZYRBRuijQ27o8w%40mail.gmail.com
<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAAEV3p%3DzhNhfOpe8x%3DRKgxYFS9GCq_q-c8knZYRBRuijQ27o8w%40mail.gmail.com>
Intent to Extend Experiment 1:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6a45fcf5.198129d7.1d0cd0.0014.GAE%40google.com
<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6a45fcf5.198129d7.1d0cd0.0014.GAE%40google.com>
This intent message was generated by Chrome Platform
Status <https://chromestatus.com>.
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