Patterns: Speed up the Patterns screen on sites with many patterns by MaggieCabrera · Pull Request #85234 · WordPress/gutenberg

MaggieCabrera · 2026-10-20T20:11:56Z

What?

Follow-up to the performance review of #84507. The site editor's Patterns screen no longer freezes on sites with lots of patterns. With 2,000 extra patterns registered, the first previews show in about 1 s instead of 3.4 s.

Opening Appearance > Editor > Patterns	Before	After
Main-thread time	3,329 ms	920 ms
Longest task	2,487 ms	117 ms
First preview shown	3,350 ms	991 ms

Medians of 7 runs with Playwright, CDP Performance.getMetrics and a long task observer, on Twenty Twenty-Five plus a test plugin that registers 2,000 copies of its patterns. With 4× CPU throttling, the longest task goes from 10.6 s to 0.8 s.

Why?

The Patterns screen parsed every theme, plugin and core pattern as soon as it loaded, even though it only shows 20 per page. It also removed duplicate names with a findIndex inside a filter, which slows down quickly as the list grows. Sites with lots of plugin or theme patterns already hit this today, and #84507 would add many more.

How?

A pattern's blocks are parsed the first time its preview reads them, and cached per pattern. It's the approach the block editor store has used since Reusable blocks: fix performance of __experimentalGetAllowedPatterns #64871.
The extensible site editor already parses in the preview, so it only gets the faster dedupe.
edit-site gets a tsconfig.test.json, like packages/grid, so the new tests can be TypeScript.

Testing Instructions

Install the test plugin from the first comment, or any plugin that registers a few thousand patterns.
Go to Appearance > Editor > Patterns. It opens without the long freeze, and the previews look the same as on trunk.
Switch categories, search and change pages. The previews still show as on trunk.

Testing Instructions for Keyboard

No UI changes.

Use of AI Tools

Written with Claude Code (Claude Opus 5.5), including the test plugin and the measuring script. I reviewed the changes and checked the numbers.

🤖 Generated with Claude Code

The Patterns screen parsed the blocks of every theme, plugin and core pattern up front, and removed duplicate names with a findIndex inside a filter. With thousands of patterns both are slow. Blocks are now parsed when a preview first reads them and cached per pattern, and duplicates are removed in one pass. The extensible site editor gets the same dedupe; it already parses in the preview. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

github-actions · 2026-10-20T20:12:09Z

🤖 PR meta 🤖

📦 Bundle size

Size Change: +67 B (0%)

Total Size: 9.05 MB

📦 View Changed

Filename	Size	Change
`build/scripts/edit-site/index.min.js`	420 kB	+67 B (+0.02%)

_{37c49c6 Run}

⚡ Performance

Show the results

Client side metrics exclude the server response time.

front-end-block-theme

Metric	`509d969`	trunk	% Change
timeToFirstByte	52.65 ms +10.64% -3.32%	53.6 ms +12.59% -6.34%	-1.77%
largestContentfulPaint	96 ms +4.17% -10.42%	92 ms +2.17% -4.35%	4.35%
lcpMinusTtfb	38.75 ms +15.23% -11.74%	36.1 ms +14.68% -7.76%	7.34%
wpBeforeTemplate	27.28 ms +19.39% -1.47%	27.28 ms +19.72% -2.09%	0%
wpTemplate	20.6 ms +2.86% -3.59%	20.24 ms +5.48% -2.57%	1.78%
wpTotal	48.61 ms +11.38% -3.5%	49.6 ms +11.33% -6.53%	-2%
wpMemoryUsage	7.64 MB +0% -0%	7.61 MB +0% -0%	0.46%
wpDbQueries	16 +0% -0%	16 +0% -0%	0%

front-end-classic-theme

Metric	`509d969`	trunk	% Change
timeToFirstByte	43.75 ms +6.74% -3.31%	42.6 ms +9.15% -0.94%	2.7%
largestContentfulPaint	100 ms +2% -4%	96 ms +4.17% -0%	4.17%
lcpMinusTtfb	54.9 ms +1.91% -2%	53.6 ms +1.21% -0.47%	2.43%
wpBeforeTemplate	24.19 ms +6.53% -1.94%	23.67 ms +5.2% -0.89%	2.2%
wpTemplate	15.91 ms +4.15% -2.95%	15.76 ms +6.03% -1.84%	0.95%
wpTotal	40.55 ms +6.63% -3.4%	39.32 ms +8.83% -0.46%	3.13%
wpMemoryUsage	6.33 MB +0% -0%	6.30 MB +0% -0%	0.57%
wpDbQueries	13 +0% -0%	13 +0% -0%	0%

media-processing

Metric	`509d969`	trunk	% Change
mediaProcessingJpeg	418.37 ms +0.77% -0.82%	412.34 ms +2.15% -0.03%	1.46%
mediaProcessingAvif	6166.01 ms +0.22% -0.03%	6166.71 ms +0.27% -0.25%	-0.01%
mediaProcessingJpegToAvif	4313.32 ms +0.17% -0.07%	4327.12 ms +0.21% -0.42%	-0.32%

media-upload

Metric	`509d969`	trunk	% Change
jpegUploadProcessing	1926.01 ms +0.62% -24.4%	1442.2 ms +1.99% -1.18%	33.55%
pngUploadProcessing	218.76 ms +10.08% -14.01%	207.92 ms +3.86% -11.62%	5.21%
largeJpegUploadProcessing	1428.7 ms +1.12% -0.53%	1423.64 ms +0.53% -0.38%	0.36%
multipleImageUploadProcessing	2056.86 ms +1.27% -7.31%	1600.48 ms +28.74% -0.86%	28.52%

post-editor

Metric	`509d969`	trunk	% Change
serverResponse	490.66 ms +7.09% -4.86%	498.21 ms +2.8% -1.26%	-1.52%
firstPaint	302.26 ms +66.75% -17.45%	519.96 ms +2.61% -15.86%	-41.87%
domContentLoaded	1208.4 ms +2.15% -3.14%	1203.83 ms +2% -1.65%	0.38%
loaded	1209.62 ms +2.14% -3.16%	1205.05 ms +1.99% -1.68%	0.38%
firstContentfulPaint	523.02 ms +1.89% -3.63%	519.96 ms +2.61% -2.24%	0.59%
firstBlock	3697.65 ms +3.25% -3.6%	3670.67 ms +3.3% -1.87%	0.74%
type	18.16 ms +6.55% -5.95%	18.02 ms +7.88% -5.94%	0.78%
typeWithoutInspector	19.04 ms +4.1% -8.77%	18.05 ms +6.87% -3.27%	5.48%
typeWithTopToolbar	25.23 ms +3.37% -2.77%	23.4 ms +5.26% -2.65%	7.82%
typeContainer	8.89 ms +10.57% -2.14%	9.84 ms +3.96% -11.89%	-9.65%
focus	117.46 ms +4.03% -1.86%	116.53 ms +3.49% -3.2%	0.8%
firstFocus	240.47 ms +0% -0%	242.98 ms +0% -0%	-1.03%
selectAll	573.03 ms +6.13% -3.51%	600.6 ms +2.75% -0.11%	-4.59%
listViewOpen	79.25 ms +8.64% -6.56%	82.26 ms +6.94% -6.54%	-3.66%
inserterOpen	42.82 ms +8.94% -9.86%	40.58 ms +7.64% -5.84%	5.52%
inserterHover	12 ms +7.58% -10.83%	11.17 ms +8.86% -4.21%	7.43%
inserterSearch	8.07 ms +9.29% -7.19%	9.14 ms +2.19% -7.55%	-11.71%
loadPatterns	639.79 ms +2.46% -2.45%	667.85 ms +6.12% -1.77%	-4.2%
wpTotal	480.42 ms +7.33% -4.83%	488.41 ms +2.82% -1.31%	-1.64%
wpMemoryUsage	14.66 MB +0% -0%	14.63 MB +0% -0%	0.26%
wpDbQueries	55 +0% -1.82%	55 +0% -1.82%	0%

site-editor

Metric	`509d969`	trunk	% Change
serverResponse	305.26 ms +4.75% -7.33%	288.39 ms +5.37% -3.67%	5.85%
firstPaint	187.23 ms +28.34% -10.71%	207.99 ms +10.12% -16.54%	-9.98%
domContentLoaded	947.45 ms +1.09% -1.59%	952.08 ms +0.72% -1.48%	-0.49%
loaded	948.52 ms +1.08% -1.62%	953.01 ms +0.69% -1.46%	-0.47%
firstContentfulPaint	345.19 ms +7.64% -12.28%	384.7 ms +4.21% -30.07%	-10.27%
firstBlock	3586.91 ms +0.25% -0.24%	3572.04 ms +1.08% -0.72%	0.42%
type	15.95 ms +3.45% -1.38%	15.57 ms +1.67% -3.28%	2.44%
navigate	96.57 ms +4.98% -9.46%	97.96 ms +2.24% -8.43%	-1.42%
loadPatterns	1012.5 ms +20.53% -1.45%	977.5 ms +15.61% -5.13%	3.58%
loadPages	1023.61 ms +3.99% -1.34%	1038.02 ms +1.9% -2.96%	-1.39%
wpTotal	297.15 ms +4.86% -7.52%	280.37 ms +5.58% -3.72%	5.98%
wpMemoryUsage	12.70 MB +0% -0%	12.66 MB +0% -0%	0.29%
wpDbQueries	44 +2.27% -0%	44 +2.27% -0%	0%

_{37c49c6 Run}

🏁 Flaky tests

Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

Regression: updating a specific option will only change its value and will not corrupt others in /test/e2e/specs/editor/various/core-settings.spec.js, passed after 1 failed attempt.

Error: expect(received).toStrictEqual(expected) // deep equality

- Expected  - 1
+ Received  + 1

  Array [
    "rewrite_rules",
-   "SERIALIZED DATA",
+   "",
  ]
    at forEach (/home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/various/core-settings.spec.js:46:26)
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/various/core-settings.spec.js:43:35

refuses the drop and uploads nothing in /test/e2e/specs/editor/various/single-file-placeholder-drop.spec.js, passed after 1 failed attempt.

Error: expect(received).toHaveLength(expected)

Expected length: 0
Received length: 1
Received array:  [{"_links": {"about": [{"href": "http://localhost:8889/wp-json/wp/v2/types/attachment"}], "author": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/users/1"}], "collection": [{"href": "http://localhost:8889/wp-json/wp/v2/media"}], "curies": [{"href": "https://api.w.org/{rel}", "name": "wp", "templated": true}], "replies": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/comments?post=223"}], "self": [{"href": "http://localhost:8889/wp-json/wp/v2/media/223", "targetHints": {"allow": ["GET", "POST", "PUT", "PATCH", "DELETE"]}}], "wp:attached-to": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/posts/222", "id": 222, "post_type": "post"}]}, "alt_text": "", "author": 1, "caption": {"rendered": ""}, "class_list": ["post-223", "attachment", "type-attachment", "status-inherit", "hentry", "entry"], "comment_status": "open", "date": "2026-10-20T20:29:48", "date_gmt": "2026-10-20T20:29:48", "description": {"rendered": "<p class=\"attachment\"><a href='http://localhost:8889/wp-content/uploads/2026/10/12590a61-dddc-4c2a-bb08-82765e12cb8d.png'><img loading=\"lazy\" decoding=\"async\" width=\"10\" height=\"10\" src=\"http://localhost:8889/wp-content/uploads/2026/10/12590a61-dddc-4c2a-bb08-82765e12cb8d.png\" class=\"attachment-medium size-medium\" alt=\"\" style=\"width:100%;height:100%;max-width:10px;\" /></a></p>
"}, "featured_media": 0, "filename": "12590a61-dddc-4c2a-bb08-82765e12cb8d.png", "filesize": 80, "guid": {"rendered": "http://localhost:8889/wp-content/uploads/2026/10/12590a61-dddc-4c2a-bb08-82765e12cb8d.png"}, "id": 223, "link": "http://localhost:8889/?attachment_id=223", "media_details": {"file": "2026/10/12590a61-dddc-4c2a-bb08-82765e12cb8d.png", "filesize": 80, "height": 10, "image_meta": {"alt": "", "aperture": "0", "camera": "", "caption": "", "copyright": "", "created_timestamp": "0", "credit": "", "focal_length": "0", "iso": "0", "keywords": [], "orientation": "0", "shutter_speed": "0", "title": ""}, "sizes": {}, "width": 10}, "media_type": "image", "meta": [], "mime_type": "image/png", "modified": "2026-10-20T20:29:48", "modified_gmt": "2026-10-20T20:29:48", "ping_status": "closed", "post": 222, "slug": "12590a61-dddc-4c2a-bb08-82765e12cb8d", "source_url": "http://localhost:8889/wp-content/uploads/2026/10/12590a61-dddc-4c2a-bb08-82765e12cb8d.png", "status": "inherit", "template": "", "title": {"rendered": "12590a61-dddc-4c2a-bb08-82765e12cb8d"}, "type": "attachment"}]
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/various/single-file-placeholder-drop.spec.js:71:45

submenu converts to link automatically in /test/e2e/specs/editor/blocks/navigation.spec.js, passed after 1 failed attempt.

Error: apiRequestContext.fetch: socket hang up
Call log:
  - → POST http://localhost:8889/wp-json/wp/v2/navigation
    - user-agent: Playwright/1.63.0 (x64; ubuntu 24.04) node/24.20 CI/1
    - accept: */*
    - accept-encoding: gzip,deflate,br
    - X-WP-Nonce: 7fc4276d2d
    - content-type: application/json
    - content-length: 356
    - cookie: wordpress_test_cookie=WP%20Cookie%20check; wordpress_logged_in_23778236db82f19306f247e20a353a99=admin%7C1792700390%7CLf5UeVYoOACZgVdBuMzfDb6DH9DJXzd3SvDVPFQ6NdA%7Ca0bb159bbb9b912a5d488ae92cbafb30b6c7f9d3f9a63063010b39a30358ad11; wp-settings-time-1=1792527720

    at RequestUtils.rest (/home/runner/work/gutenberg/gutenberg/packages/e2e-test-utils-playwright/src/request-utils/rest.ts:112:39)
    at RequestUtils.createRecord (/home/runner/work/gutenberg/gutenberg/packages/e2e-test-utils-playwright/src/request-utils/records.ts:20:14)
    at RequestUtils.createNavigationMenu (/home/runner/work/gutenberg/gutenberg/packages/e2e-test-utils-playwright/src/request-utils/menus.ts:63:14)
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/blocks/navigation.spec.js:226:23

three users concurrently edit a large post with diverse blocks in /test/e2e/specs/editor/collaboration/collaboration-stress.spec.ts, passed after 1 failed attempt.

TimeoutError: locator.waitFor: Timeout 17500ms exceeded.
Call log:
  - waiting for getByRole('button', { name: /Collaborators list/ }) to be visible

    at map (/home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/collaboration/fixtures/collaboration-utils.ts:193:7)
    at CollaborationUtils.waitForMutualDiscovery (/home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/collaboration/fixtures/collaboration-utils.ts:188:10)
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/collaboration/collaboration-stress.spec.ts:416:28

_{37c49c6 Run}

MaggieCabrera added [Type] Performance Related to performance efforts [Feature] Patterns A collection of blocks that can be synced (previously reusable blocks) or unsynced labels Oct 20, 2026

Add the PR number to the edit-site changelog entry

37c49c6

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

github-actions Bot added the [Package] Edit Site /packages/edit-site label Oct 20, 2026

MaggieCabrera mentioned this pull request Oct 21, 2026

Patterns: Use patterns from other installed themes #84507

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Patterns: Speed up the Patterns screen on sites with many patterns - #85234

Patterns: Speed up the Patterns screen on sites with many patterns#85234
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edited

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MaggieCabrera commented Oct 20, 2026

What?

Why?

How?

Testing Instructions

Testing Instructions for Keyboard

Use of AI Tools

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🤖 PR meta 🤖

📦 Bundle size

⚡ Performance

🏁 Flaky tests

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