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DMAIC Phase 1 — Define the performance problem. Scope the symptom, classify it, set measurable targets, identify the affected user flow, and produce a structured problem statement. Use before measuring to avoid wasted profiling time.
Codex または Claude でインストール この Prompt をコピーして Codex、Claude、または他のアシスタントに貼り付けると、Skill ページを確認してインストールできます。
SOC 職業分類に基づく
| name | perf-define |
| description | DMAIC Phase 1 — Define the performance problem. Scope the symptom, classify it, set measurable targets, identify the affected user flow, and produce a structured problem statement. Use before measuring to avoid wasted profiling time. |
| effort | low |
| argument-hint | [symptom description or screen name] |
| tools | Read, Glob, Grep, Bash |
Scope the performance problem before investing time in profiling. A well-defined problem leads directly to the correct measurement tool.
/perf-define "Home screen scrolls at 30fps on Android"
/perf-define "App takes 5 seconds to start on low-end devices"
/perf-define "Bundle is 12MB and growing"
Classify the user's reported symptom into one of these domains:
| Domain | Symptoms | Measurement Tool | Next Skill |
|---|---|---|---|
| FPS / Jank | Dropped frames, stuttering scroll, laggy touch response | Flashlight (Android), React Perf Monitor | /perf-measure fps |
| Startup / TTI | Slow cold start, splash screen lingers, delayed interactivity | react-native-performance markers, Flashlight | /perf-measure tti |
| Bundle / App Size | Large download, slow OTA updates, Play Store warnings | source-map-explorer, Expo Atlas, Ruler | /perf-measure bundle |
| Memory | Growing RAM usage, OOM crashes, GC pauses | React DevTools Memory, Xcode Leaks, Android Memory Profiler | /perf-measure memory |
| Animation | Choppy animations, gesture lag, non-60fps transitions | Flashlight + Reanimated inspector | /perf-measure animation |
Ask or determine:
Search the codebase for the affected screen:
find . -name "*.tsx" -path "*Screen*" | grep -i "[screen-name]"
Frame the problem in terms of user impact:
Reference ${CLAUDE_SKILL_DIR}/references/metric-targets.md for thresholds.
Define:
Use the template from ${CLAUDE_SKILL_DIR}/references/problem-statement-template.md:
On [platform/device tier], [user action] causes [observed symptom],
measured at [current metric]. Target: [goal metric].
Hypothesis: [suspected area].
Affected flow: [navigation path to reproduce].
Save the problem statement for reference by later DMAIC phases:
.perf/[slug]/define.md
After completing the definition, recommend:
/perf-measure [domain] to collect baseline metrics."/perf-quick first for a fast scan."native-measure-tti.md — TTI measurement markers setupjs-measure-fps.md — FPS monitoring approachesbundle-analyze-js.md — Bundle size measurementjs-memory-leaks.md — Memory leak identificationDMAIC Phase 3 — Root cause analysis. Takes baseline metrics from /perf-measure and maps them to root causes using pattern matching. Searches the codebase for supporting evidence. Produces a ranked hypothesis list with confidence levels.
DMAIC Phase 4 — Apply targeted fixes. Takes a root cause from /perf-analyze and presents an ordered improvement checklist. Prioritizes battle-tested library substitutions over custom code, then code-level fixes, then architecture changes.
DMAIC Phase 2 — Collect performance data. Routes to the correct measurement tool based on symptom domain (FPS, TTI, bundle, memory, animation). Guides profiling setup, interprets tool output, and produces a structured baseline metrics report.
DMAIC Phase 5 — Prevent regressions. Sets up callstack/reassure for render/interaction benchmarks, configures Flashlight for CI, adds bundle size thresholds, and documents the performance baseline. Use after /perf-improve to lock in gains.
Fast 5-minute React Native performance audit. Scans source for the 12 most impactful antipatterns without profiling — code-level grep scan only. Use as a first pass before deeper DMAIC investigation.