[Docs] Make docs build faster

[weronikaolejniczak]

Summary

Closes https://github.com/elastic/eui-private/issues/762

What:

• Enable Docusaurus Faster. It doesn't work out-of-box because SWC skips babel.config.js, so we have to configure it to compile JSX with Emotion’s runtime (importSource: '@emotion/react') instead of the default React runtime.
• Reuse the react-docgen-typescript parser across files instead of creating one per file (~1394x). Previously it was in a loop.

Local timings (Docusaurus build only, workspaces already built):

• Webpack baseline: ~2m 23s vs Faster + Emotion SWC: ~24s
• Docgen: ~74s → ~22s

Benchmark

Step	n2d8 only (#9984)	Faster + docgen	Saved
yarn	39s	40s	0
@elastic/eui compile + other workspaces	~2.5m	~2.5m	~0
docgen parse	77s	36s	41s
typedoc	29s	29s	0
Docusaurus	3.7m (webpack client 2.91m)	48s	~2.9m
GCS	9s	9s	0
website job	8m58s	5m20s	~3.6m

QA instructions for reviewer

• Smoke test PR docs preview,
  • home page typewriter effect,
  • CSS-heavy pages like Button,
  • misbehaving pages like Empty prompt,
  • verify showing the source and changing the source works as expected,
  • verify the examples render correctly...
• make sure docgen maintains the same shape (e.g. you can smoke-test prop tables in docs).

[Copilot]

🔵 Needs a closer look

It changes core docs build tooling/CI execution characteristics (experimental Faster/Rspack/SWC + larger agents) and should be validated by a human reviewer in CI and preview deployments.

Pull request overview

Speeds up the EUI docs deploy pipeline by enabling Docusaurus “Faster” (Rspack/SWC-based build path), increasing CI agent resources, and reducing overhead in the docgen generation step.

Changes:

• Enable future.experimental_faster in Docusaurus and configure SWC to use Emotion’s JSX runtime (importSource: '@emotion/react').
• Add @docusaurus/faster dependency (and corresponding lockfile updates).
• Reuse a single react-docgen-typescript parser instance across files and increase Buildkite deploy-docs agent size.

File summaries

File	Description
yarn.lock	Adds lock entries for @docusaurus/faster and its transitive deps (Rspack/SWC/etc.).
packages/website/package.json	Adds @docusaurus/faster@3.7.0 to website dependencies.
packages/website/docusaurus.config.ts	Enables Docusaurus Faster and customizes SWC loader options for Emotion’s automatic runtime.
packages/eui-docgen/src/main.ts	Reuses a docgen parser across files and adjusts per-file state handling.
.buildkite/pipelines/deploy_docs.yml	Upgrades deploy-docs agent machine type to n2d-standard-8 for faster builds.

Review details

• Files reviewed: 4/5 changed files
• Comments generated: 1
• Review effort level: Lite

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[mgadewoll]

🟢 Changes are LGTM, left one comment. Great update to speed up the build! 🎉

[infra-vault-gh-plugin-prod]

💚 Build Succeeded

• Buildkite Build
• Commit: 02ac63f

History

• 💚 Build #7770 succeeded 0d21aa9
• 💚 Build #7760 succeeded 89a40d6
• 💚 Build #7756 succeeded 5897fdb
• 💚 Build #7753 succeeded 04530c8

[infra-vault-gh-plugin-prod]

💚 Build Succeeded

• Buildkite Build
• Commit: 02ac63f
• Documentation website
• Storybook
• ✅ Visual regression tests passed

History

• 💚 Build #5179 succeeded 0d21aa9
• 💚 Build #5167 succeeded 89a40d6
• 💚 Build #5162 succeeded 5897fdb
• 💚 Build #5159 succeeded 04530c8