perf: deduplicate identical hoisted templates within a component#18320
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Rich-Harris merged 3 commits intoMay 29, 2026
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Byte-identical templates hoisted from different fragments/elements/branches now share a single `$.from_html` factory instead of each emitting its own module-scope variable. Reduces generated code size and avoids redundant runtime template parsing. Dedup is keyed on `(content, flags)` and skipped in dev mode (where templates are wrapped in `$.add_locations`). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
🦋 Changeset detectedLatest commit: 4faf241 The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.56.0 ### Minor Changes - feat: allow declarations in the template ([#18282](#18282)) ### Patch Changes - perf: use `createElement` instead of `createElementNS` for HTML elements ([#18262](#18262)) - perf: store `current_sources` as a `Set` for O(1) membership checks ([#18278](#18278)) - perf: deduplicate identical hoisted templates within a component ([#18320](#18320)) - perf: hoist `rest_props` exclude list as a module-scope `Set` ([#18252](#18252)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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Byte-identical templates hoisted from different fragments, elements, or branches now share a single
$.from_htmlfactory instead of each emitting its own module-scope variable - this shrinks generated output and avoids redundant runtime template parsing. Dedup is keyed on(content, flags)and is skipped in dev mode (templates there are wrapped in$.add_locations, which embeds per-call-site info).Before submitting the PR, please make sure you do the following
feat:,fix:,chore:, ordocs:.packages/svelte/src, add a changeset (npx changeset).Tests and linting
pnpm testand lint the project withpnpm lint