motormetrics: Skill for Claude Code

Performance Skill

Performance Targets

Frontend (Web Vitals): LCP < 2.5s, FID < 100ms, CLS < 0.1, FCP < 1.8s, TTFB < 600ms Backend: Response time < 500ms (p95), cold start < 2s, error rate < 1% Database: Query time < 100ms, cache hit rate > 80%

Measure Performance

# Lighthouse audit
npx lighthouse https://sgcarstrends.com --view

# Bundle analysis
cd apps/web && ANALYZE=true pnpm build

# Load test with k6
k6 run --vus 100 --duration 5m load-test.js

Bundle Size Optimization

Dynamic Imports

// ❌ Static import (loads immediately)
import { HeavyComponent } from "./heavy-component";

// ✅ Dynamic import (lazy load)
import dynamic from "next/dynamic";
const HeavyComponent = dynamic(() => import("./heavy-component"), {
  loading: () => <div>Loading...</div>,
  ssr: false,
});

Tree Shaking

// ❌ Imports entire library
import _ from "lodash";

// ✅ Import only what you need
import uniq from "lodash/uniq";

React Performance

Prevent Re-renders

// useMemo for expensive calculations
const processed = useMemo(() => expensiveOperation(data), [data]);

// useCallback for stable function references
const handleClick = useCallback(() => doSomething(), []);

// React.memo for pure components
const Child = React.memo(function Child({ name }) {
  return <div>{name}</div>;
});

Virtualize Long Lists

import { FixedSizeList } from "react-window";

<FixedSizeList height={600} itemCount={items.length} itemSize={100} width="100%">
  {({ index, style }) => <Item style={style} data={items[index]} />}
</FixedSizeList>

Database Query Optimization

Add Indexes

// packages/database/src/schema/cars.ts
export const cars = pgTable("cars", {
  make: text("make").notNull(),
  month: text("month").notNull(),
}, (table) => ({
  makeIdx: index("cars_make_idx").on(table.make),
}));

Avoid N+1 Queries

// ❌ N+1 queries
for (const post of posts) {
  post.author = await db.query.users.findFirst({ where: eq(users.id, post.authorId) });
}

// ✅ Single query with relation
const posts = await db.query.posts.findMany({ with: { author: true } });