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Frontend · Version 1.5.0 · Reviewed 2026-08-02

React Performance Reviewer

Improve render profiling and bundle analysis with evidence, explicit trade-offs, and a verification plan.

4 method steps 7 documented failure modes 5 diagnostic checks 7 quality gates

Finds unnecessary renders, unstable dependencies, large hydration boundaries, expensive effects, and bundle-loading problems in React applications.

₹199 one-time

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What this skill helps you do

  • Render profiling
  • Bundle analysis
  • State architecture review

How React Performance Reviewer works

You provide

Component code, field metrics, and the failing interaction

It inspects

Render triggers and layout stability for render profiling

It decides

A bundle analysis fix targeting the measured vital

You verify

Field Core Web Vitals and keyboard traversal re-checked

What it checks first

React Performance Reviewer finds unnecessary renders, unstable dependencies, large hydration boundaries, expensive effects, and bundle-loading problems in React applications. Use it when the work involves Render profiling, Bundle analysis, State architecture review.

  1. Whether re-renders come from changed props, changed context, or a new object identity created during render.
  2. Which Core Web Vital is failing, since LCP, INP, and CLS have completely different causes and fixes.
  3. Whether state lives at the right level, because state placed too high re-renders subtrees that never read it.
  4. Effect dependency arrays that lie, either omitting a dependency or including an unstable one.
  5. Bundle composition: whether a single dependency dominates the critical path.

Failure modes it recognizes

  • An inline object or arrow function in props defeating memoization on every render.
  • A `useEffect` that sets state derived from props, causing a double render and occasional flicker.
  • Layout shift from images and embeds without reserved dimensions, damaging CLS after content loads.
  • A long task on the main thread blocking interaction response and inflating INP.
  • Stale closure capturing an old value inside an interval or subscription callback.
  • Hydration mismatch from rendering time, randomness, or browser-only APIs during server render.
  • Focus lost after a route change, leaving keyboard and screen-reader users stranded.

Answers it will reject

  • Wrapping everything in `memo` and `useCallback`, which adds comparison cost without removing the identity churn.
  • Fixing a race by adding a timeout, which reorders the symptom instead of the cause.
  • Using `aria-label` to patch a control that should have been a native element with real semantics.
  • Measuring performance in development mode, where the framework runs extra work that does not ship.

Decision rules it applies

  • Move state down or split context before reaching for memoization.
  • Derive during render instead of synchronizing with an effect; effects are for external systems.
  • Reserve space for anything that loads asynchronously to protect layout stability.
  • Prefer native semantic elements; ARIA is a correction layer, not a foundation.

Evidence it asks for

  • Profile with the framework profiler to attribute renders to a specific trigger.
  • Collect field Core Web Vitals rather than lab scores, since lab conditions hide real-device behavior.
  • Test keyboard-only navigation and screen-reader output for any interactive change.

The method inside

  1. Map the artifact, actors, boundaries, and invariants relevant to render profiling.
  2. Trace concrete failure or abuse paths for bundle analysis; do not report checklist items without a mechanism.
  3. Prioritize state architecture review findings by impact, likelihood, confidence, and cost of correction.
  4. Recommend the smallest defensible change, then define how an independent reviewer can verify it.

Deliverables

  • Render profiling assessment
  • Bundle analysis decision and action plan
  • State architecture review verification checklist

Evidence requirements

  • Interface code, rendered behavior, and user journey
  • Browser/device matrix and accessibility tree
  • Performance and usability observations

Quality gates

  • Every material claim traces to supplied evidence or is labeled as a hypothesis.
  • The response follows the declared deliverable contract.
  • No execution, access, measurement, or verification is invented.
  • Secrets and personal data are redacted rather than repeated.
  • The user receives a concrete independent verification step.
  • The relevant failure modes in this domain were considered rather than only the reported symptom.
  • No listed anti-pattern was recommended as a solution.

Example task

Input

This React dashboard feels slow when one filter changes even though the API response is fast.

Expected output

The filter state lives above every chart, so all twelve visualization trees rerender on each keystroke. Split committed query state from draft input and memoize only the expensive chart transforms...

Boundaries and compatibility

Ideal for

  • Render profiling: produce a decision or artifact grounded in supplied evidence.
  • Bundle analysis: produce a decision or artifact grounded in supplied evidence.
  • State architecture review: produce a decision or artifact grounded in supplied evidence.

Out of scope

  • Treating automated accessibility scans as complete
  • Changing visual style without preserving behavior

Agent compatibility

  • GitHub Copilot Agent Skills
  • Cursor Agent Skills
  • Claude Code Skills
  • OpenAI Codex Skills
  • JetBrains Junie Skills

Tool policy: Advisory by default. No tools are assumed. If the host provides tools, use read-only evidence gathering unless the user explicitly approves a scoped write or execution action.