Docx editor react large performance improvement

[ResiDev]

Summary

Improves DocxEditor typing performance by reducing unnecessary React rerenders, redundant selection overlay updates, and avoidable layout work.

Changes

• Preserve selection formatting/context object identity when values are unchanged
• Stabilize toolbar context values and memoize formatting UI paths
• Move caret blinking from React state updates to CSS animation
• Avoid redundant selection overlay state updates
• Prevent layout-input effects from rerunning on ordinary body edits
• Keep layout/selection observer callbacks stable so geometry redraws do not trigger extra React work

Verification

• bun run typecheck
• bun run build
• bun test packages/react/src/paged-editor/LayoutSelectionGate.test.ts packages/react/src/paged-editor/PagedEditor.tableMeasure.test.ts
• bun test
• bun run lint (passes with existing warnings)
• bun run format:check
• Manual typing/profile verification in the editor:
  • Commit durations dropped from roughly 40-70ms spikes to about 17-25ms on my machine
  • The profiler no longer shows the earlier stream of small repeated toolbar/editor rerenders while typing
  • Paged layout and selection overlay work during typing measured in the sub-ms to ~1ms range after the render cleanup

[vercel]

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[ResiDev]

I have read the CLA Document and I hereby sign the CLA

[jedrazb]

Hey @ResiDev could you rebase the PR on main? We have 1.x release and things got slightly re-orged in the repo

[ResiDev]

Rebased this on current main and pushed the updated branch.

I made some further changes. It focuses on reducing typing-time rerenders by splitting the heavy formatting rail out of DocxEditorToolbar, preserving selectionFormatting identity when the effective formatting has not changed, memoizing stable toolbar picker work, and stabilizing table action handler identities so callback churn does not force toolbar rerenders.

From the local React Profiler typing captures, the main profile went from about 603.5ms total render time across 30 commits (20.1ms avg, 51.3ms max, 14 commits >= 10ms) to 167.6-197.5ms across 26-28 commits (6.0-7.6ms avg, 18.5-33.6ms max, 3-5 commits >= 10ms). So roughly a 67-72% reduction in total render time for this local typing sample.

[ResiDev]

I did also find a fair amount of playwright failing tests - but from the ones that I checked I think they were failing before this commit too.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
docx-editor	Ready	Preview, Comment	May 21, 2026 6:52am

[ResiDev]

Is there anything more that you need me to do on this?