perf(ActionMenu): memoize context values

[hectahertz]

Closes #

Both MenuContext.Provider and ActionListContainerContext.Provider in ActionMenu were creating new object references on every render. This caused all context consumers (menu items, anchors) to re-render even when no values actually changed.

Wrapped both context values in useMemo and extracted the inline afterSelect callback into useCallback.

Changelog

New

N/A

Changed

• Memoized MenuContext value in Menu component
• Memoized ActionListContainerContext value in Overlay component
• Extracted afterSelect into a stable useCallback

Removed

N/A

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

All 39 existing ActionMenu tests pass. This is a pure memoization change with no behavioral difference.

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github-ui (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: af32e81

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/react	Patch

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[github-actions]

⚠️ Action required

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Or, apply the integration-tests: skipped manually label to skip these checks.

[Copilot]

Pull request overview

Improves @primer/react’s ActionMenu render performance by attempting to stabilize context provider values so context consumers don’t re-render due solely to new object/function identities.

Changes:

• Memoized MenuContext.Provider value in Menu.
• Memoized ActionListContainerContext.Provider value in Overlay.
• Extracted afterSelect into a stable useCallback.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
packages/react/src/ActionMenu/ActionMenu.tsx	Memoizes context values and stabilizes afterSelect to reduce unnecessary re-renders.
.changeset/perf-action-menu-memo-context.md	Adds a patch changeset entry describing the perf improvement.

[Copilot]

menuContextValue will still change on every render because renderAnchor is reassigned to a newly-created inline function during the React.Children.map(...) pass. Since renderAnchor is in the useMemo deps, this memoization won’t prevent re-renders of MenuContext consumers in the common case. Consider memoizing renderAnchor (and/or the contents computation that sets it) so the function identity is stable when children/anchorRef haven’t changed, otherwise the useMemo here provides little/no benefit.