performance-diagnosis

name	performance-diagnosis
description	rendering cost, layout shift, re-render loops, slow interactions, LCP, hydration delay, scroll jank, bundle impact 같은 프론트엔드 성능 이슈를 분석할 때 사용합니다.

Performance Diagnosis

Use this skill when performance is the problem. Do not modify code before analysis.

Required Output

1. Symptom Summary
2. Top Possible Causes
   • probability
   • reasoning
3. Most Likely Root Cause
4. Validation Plan
   • metric
   • tool
   • expected observation
5. Improvement Plan
   • low cost to high cost
   • trade-offs
6. Priority Action Checklist

Rules

• Follow AGENTS.md.
• Mark assumptions as [Assumption].
• Focus on measurable validation.
• Avoid generic advice.
• Consider the actual app environment after package.json and app framework are created.
• Prefer low-risk improvements before structural rewrites.
• Define verification steps before implementation.

DONGCHIMI Checks

• Is the issue app-specific or caused by a shared package?
• Are response-changing params included in query keys?
• Is layout shift caused by loading, validation, image, or font states?
• Does mobile WebView need separate validation?
• Is the performance issue measurable in local browser tooling?