Switch initial viewport embeds from preconnect to dns-prefetch links by dhruvang21 · Pull Request #2256 · WordPress/performance

dhruvang21 · 2025-11-04T13:28:14Z

Summary

Relevant technical choices

Add dns-prefetch support for OD_Link_Collection::add_link()
Replace rel=preconnect with rel=dns-prefetch for embed resources.

github-actions · 2025-11-04T13:28:27Z

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Co-authored-by: dhruvang21 <dhruvang21@git.wordpress.org>
Co-authored-by: westonruter <westonruter@git.wordpress.org>
Co-authored-by: peterwilsoncc <peterwilsoncc@git.wordpress.org>

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westonruter

Thanks for the PR.

I left some feedback.

Note that for the unit test failures, you'll need to update the snapshots. You can do this by first running all the unit tests locally, for example via npm run test-php and then update the snapshots via npm run update-test-case-snapshots. At this point, you should be able to do npm run test-php again, and the tests should pass. You can then commit all the HTML file updates.

plugins/embed-optimizer/class-embed-optimizer-tag-visitor.php

dhruvang21 · 2025-11-05T07:34:26Z

@westonruter i did run command npm run test-php but it throws this error

RequestError
    at ClientRequest.<anonymous> (/var/www/wp-performance/wp-content/performance/node_modules/got/dist/source/core/index.js:970:111)
    at Object.onceWrapper (node:events:635:26)
    at ClientRequest.emit (node:events:532:35)
    at origin.emit (/var/www/wp-performance/wp-content/performance/node_modules/@szmarczak/http-timer/dist/source/index.js:43:20)
    at emitErrorEvent (node:_http_client:103:11)
    at TLSSocket.socketErrorListener (node:_http_client:506:5)
    at TLSSocket.emit (node:events:520:28)
    at emitErrorNT (node:internal/streams/destroy:170:8)
    at emitErrorCloseNT (node:internal/streams/destroy:129:3)
    at process.processTicksAndRejections (node:internal/process/task_queues:90:21)AggregateError [ETIMEDOUT]: 
    at internalConnectMultiple (node:net:1117:18)
    at internalConnectMultiple (node:net:1185:5)
    at Timeout.internalConnectMultipleTimeout (node:net:1711:5)
    at listOnTimeout (node:internal/timers:596:11)
    at process.processTimers (node:internal/timers:529:7) {
  code: 'ETIMEDOUT',
  timings: {
    start: 1762327934784,
    socket: 1762327934784,
    lookup: 1762327934809,
    connect: undefined,
    secureConnect: undefined,
    upload: undefined,
    response: undefined,
    end: undefined,
    error: 1762327935060,
    abort: undefined,
    phases: {
      wait: 0,
      dns: 25,
      tcp: undefined,
      tls: undefined,
      request: undefined,
      firstByte: undefined,
      download: undefined,
      total: 276
    }
  }
}

westonruter · 2025-11-06T17:40:29Z

i did run command npm run test-php but it throws this error

@dhruvang21 Did you follow the setup steps on the handbook page?

dhruvang21 · 2025-11-07T05:09:45Z

@westonruter yes

westonruter · 2025-11-07T20:09:31Z

OK, I'm not sure why it's not working for you. I've updated the snapshots in 16fa2b8

codecov · 2025-11-07T20:18:16Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.33%. Comparing base (695d5b8) to head (ee466f5).
⚠️ Report is 16 commits behind head on trunk.

Additional details and impacted files

@@            Coverage Diff             @@
##            trunk    #2256      +/-   ##
==========================================
+ Coverage   69.32%   69.33%   +0.01%     
==========================================
  Files          90       90              
  Lines        7746     7749       +3     
==========================================
+ Hits         5370     5373       +3     
  Misses       2376     2376

Flag	Coverage Δ
multisite	`69.33% <100.00%> (+0.01%)`	⬆️
single	`35.73% <30.00%> (+0.02%)`	⬆️

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plugins/embed-optimizer/class-embed-optimizer-tag-visitor.php

westonruter · 2025-11-17T06:44:10Z

Based on @peterwilsoncc's comment, it seems I was overly aggressive in the switch to dns-prefeth. There would still be value to have some preconnect links, when they are used directly on the page and not exclusively in an iframe.

…efetch

dhruvang21 · 2025-12-02T07:16:27Z

@westonruter how should we move further here?

… patch-1

Copilot

Pull request overview

Updates Embed Optimizer’s resource-hint generation to avoid wasted cross-origin preconnect usage by switching affected hints to dns-prefetch, and refreshes related test fixtures across plugins.

Changes:

Switch Embed Optimizer’s generated resource hints from preconnect to dns-prefetch for embed-related hosts.
Extend Optimization Detective’s link-attribute PHPStan type to include dns-prefetch.
Update Image Prioritizer and Embed Optimizer expected HTML fixtures to match updated output.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
plugins/optimization-detective/class-od-link-collection.php	Extends LinkAttributes `rel` type to include `dns-prefetch`.
plugins/embed-optimizer/class-embed-optimizer-tag-visitor.php	Replaces preconnect-link injection with dns-prefetch-link injection for embeds.
plugins/image-prioritizer/tests/test-cases/video-without-poster-lcp-element-on-desktop-only/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/video-with-poster-lcp-element-on-mobile-and-desktop-but-not-tablet/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/video-with-poster-lcp-element-on-desktop-only/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/video-with-poster-lcp-element-on-all-breakpoints/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/video-with-large-poster-and-desktop-url-metrics-missing/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/video-with-large-poster-and-desktop-url-metrics-collected/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/url-metric-only-captured-for-one-breakpoint/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/preload-links-with-one-half-stale-group/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/picture-element-as-lcp-tablet-and-desktop-metrics-missing/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/only-mobile-and-desktop-groups-are-populated/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/no-url-metrics/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/no-url-metrics-with-non-background-image-style/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/no-url-metrics-with-data-url-image/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/no-url-metrics-with-data-url-background-image/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/no-url-metrics-for-image-without-src/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/no-url-metrics-but-server-side-heuristics-added-fetchpriority-high/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/multiple-videos-with-desktop-metrics-missing/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/multiple-videos-on-all-breakpoints/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/lcp-element-external-background-image-present-in-document-and-partially-populated-samples/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/img-non-native-lazy-loading/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/fetch-priority-high-on-lcp-image-common-on-mobile-and-desktop-with-url-metrics-missing-in-other-groups/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/different-lcp-elements-for-two-non-consecutive-breakpoints/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/different-lcp-elements-for-two-non-consecutive-breakpoints-and-one-is-stale/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/different-lcp-elements-for-non-consecutive-viewport-groups-with-missing-data-for-middle-group/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/different-lcp-elements-for-all-breakpoints/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/common-lcp-image-with-old-xpath-format/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/common-lcp-image-with-fully-incomplete-sample-data/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/image-prioritizer/tests/test-cases/background-image-outside-viewport-with-desktop-metrics-missing/expected.html	Updates expected script-tag attribute ordering in fixture output.
plugins/embed-optimizer/tests/test-cases/single-youtube-embed-outside-viewport-on-mobile/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/single-youtube-embed-inside-viewport/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/single-youtube-embed-inside-viewport-with-only-mobile-url-metrics/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/single-wordpress-tv-embed-outside-viewport-on-mobile/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/single-wordpress-tv-embed-inside-viewport/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/single-twitter-embed-outside-viewport-on-mobile/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/single-twitter-embed-inside-viewport/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/single-twitter-embed-inside-viewport-without-resized-data/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/single-twitter-embed-inside-viewport-one-group/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/figures-with-fancy-ids/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.
plugins/embed-optimizer/tests/test-cases/all-embeds-inside-viewport/expected.html	Updates expected resource-hint links from `preconnect` to `dns-prefetch`.

Comments suppressed due to low confidence (1)

plugins/embed-optimizer/class-embed-optimizer-tag-visitor.php:284

Typo in the docblock: "dns-prefech" should be "dns-prefetch".

	 * Gets dns-prefech URLs based on embed type.
	 *

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plugins/optimization-detective/class-od-link-collection.php

plugins/embed-optimizer/class-embed-optimizer-tag-visitor.php

… test

…gin embeds - Update Embed_Optimizer_Tag_Visitor to use dns-prefetch instead of preconnect. - Add support and validation for dns-prefetch in OD_Link_Collection. - Update plugin headers, readme.txt, and documentation for consistency. Co-authored-by: gemini-cli <176961590+gemini-code-assist[bot]@users.noreply.github.com>

westonruter

Sorry for the delay in reviewing this!

dhruvang21 requested review from adamsilverstein and westonruter as code owners November 4, 2025 13:28

westonruter requested changes Nov 4, 2025

View reviewed changes

dhruvang21 requested a review from felixarntz as a code owner November 5, 2025 07:28

dhruvang21 requested a review from westonruter November 6, 2025 05:11

westonruter added this to the embed-optimizer n.e.x.t milestone Nov 7, 2025

westonruter added [Type] Bug An existing feature is broken [Plugin] Embed Optimizer Issues for the Embed Optimizer plugin (formerly Auto Sizes) labels Nov 7, 2025

westonruter requested changes Nov 7, 2025

View reviewed changes

dhruvang21 force-pushed the patch-1 branch from 16fa2b8 to 7443ab6 Compare November 10, 2025 05:14

dhruvang21 requested a review from westonruter November 10, 2025 05:35

dhruvang21 and others added 5 commits November 25, 2025 12:49

Embed Optimizer: Switch cross-origin embeds from preconnect to dns-pr…

8dee6b0

…efetch

refactor: code suggestion

e059dd3

fix: phpstan

a7ae4ea

Update code comments

879fb25

Fix: phpunit test cases

7e04b2f

dhruvang21 force-pushed the patch-1 branch from 7ac738a to 7e04b2f Compare November 25, 2025 07:19

dhruvang21 added 2 commits November 28, 2025 18:58

Merge branch 'trunk' into patch-1

578e5b7

Merge branch 'trunk' into patch-1

0f8f3f2

dhruvang21 added 3 commits December 12, 2025 16:14

Merge branch 'trunk' into patch-1

fdff928

Merge branch 'trunk' into patch-1

35f941f

Merge branch 'trunk' into patch-1

51b3603

westonruter mentioned this pull request Jan 11, 2026

Embed Optimizer wastefully adds preconnect links for initial-viewport embeds when only dns-prefetch is used #2247

Closed

Merge branch 'trunk' of https://github.com/WordPress/performance into…

6548f24

… patch-1

westonruter requested a review from Copilot February 27, 2026 00:02

Copilot started reviewing on behalf of westonruter February 27, 2026 00:02 View session

Copilot AI reviewed Feb 27, 2026

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plugins/optimization-detective/class-od-link-collection.php Show resolved Hide resolved

plugins/embed-optimizer/class-embed-optimizer-tag-visitor.php Show resolved Hide resolved

westonruter added the [Plugin] Optimization Detective Issues for the Optimization Detective plugin label Feb 27, 2026

westonruter and others added 3 commits February 26, 2026 16:49

Update snapshots

3eb4db3

Add test case for bad dns-prefetch for OD_Link_Collection::add_link()…

9fe7b7e

… test

westonruter force-pushed the patch-1 branch from 81ada24 to 348b35d Compare February 27, 2026 00:49

westonruter approved these changes Feb 27, 2026

View reviewed changes

Add code formatting for dns-prefetch

ee466f5

westonruter changed the title ~~Embed Optimizer: Switch cross-origin embeds from preconnect to dns-pr…~~ Embed Optimizer: Switch cross-origin embeds from preconnect to dns-prefetch Feb 27, 2026

westonruter changed the title ~~Embed Optimizer: Switch cross-origin embeds from preconnect to dns-prefetch~~ Switch initial viewport embeds from preconnect to dns-prefetch Feb 27, 2026

westonruter changed the title ~~Switch initial viewport embeds from preconnect to dns-prefetch~~ Switch initial viewport embeds from preconnect to dns-prefetch links Feb 27, 2026

westonruter merged commit ee918b1 into WordPress:trunk Feb 27, 2026
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dhruvang21 commented Nov 4, 2025 •

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