# react-optimise

A skill that walks through React app performance: React Compiler, bundle size, rendering, data fetching, Core Web Vitals. Useful when your app feels slow.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 396 installs · ★ 218
- Author: pproenca
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/pproenca/dot-skills/tree/HEAD/skills/.experimental/react-optimise/SKILL.md
- Updated: 2026-08-15
- HTML: https://affpapa.org/en/nevibecode/skills/react-optimise

## What it does

The skill packs 43 rules across 8 categories, ranked by impact from critical down to incremental. Topics include React Compiler adoption, bundle splitting and loading, render optimization, data fetching speed, Core Web Vitals, state subscriptions, profiling, and memory management.

Rules live in separate files under `references/`. There is one on silent compiler bailouts, one on eliminating barrel files, one on virtualizing long lists with TanStack Virtual. A quick reference section lists the critical patterns and the mistakes people keep making.

React 19 API usage is out of scope — that belongs to the `react` skill. Next.js-specific features are also excluded; see `nextjs-16-app-router`. If you want Next.js recipes, this skill won't give them to you.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill react-optimise -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/react-optimise/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/react-optimise/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill react-optimise -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/react-optimise/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill react-optimise -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/react-optimise/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install pproenca/dot-skills react-optimise
```

2. **Manually: put the files in place**
- File: `.github/skills/react-optimise/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill react-optimise -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/pproenca/dot-skills --path skills/.experimental/react-optimise
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/react-optimise/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add pproenca/dot-skills --skill react-optimise -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/pproenca/dot-skills/tree/HEAD/skills/.experimental/react-optimise/SKILL.md

## When to use it
- figure out why components aren't being memoized automatically
- shrink the initial bundle by splitting at route boundaries
- remove sequential data fetches that slow down page loads
- track down memory leaks in a long-lived SPA
- improve INP, LCP and CLS using real user data

## Example prompts
- analyze the bundle size and suggest what to move into dynamic imports
- why isn't React Compiler optimizing this component?
- help me remove the data fetching waterfall on the profile page

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 4f94a3f442063f72.

BEGIN THIRD-PARTY FILE 4f94a3f442063f72
```text
---
name: react-optimise
description: Application-level React performance optimization covering React Compiler mastery, bundle optimization, rendering performance, data fetching, Core Web Vitals, state subscriptions, profiling, and memory management. Use when optimizing React app performance, analyzing bundle size, improving Core Web Vitals, or profiling render bottlenecks. Complements the react skill (API-level patterns) with holistic performance strategies. Does NOT cover React 19 API usage (see react skill) or Next.js-specific features (see nextjs-16-app-router skill).
---

# React Optimise Best Practices

Application-level performance optimization guide for React applications. Contains 43 rules across 8 categories, prioritized by impact from critical (React Compiler, bundle optimization) to incremental (memory management).

## When to Apply

- Optimizing React application performance or bundle size
- Adopting or troubleshooting React Compiler v1.0
- Splitting bundles and configuring code splitting
- Improving Core Web Vitals (INP, LCP, CLS)
- Profiling render performance and identifying bottlenecks
- Fixing memory leaks in long-lived single-page applications
- Optimizing data fetching patterns and eliminating waterfalls

## Rule Categories

| Category | Impact | Rules | Key Topics |
|----------|--------|-------|------------|
| React Compiler Mastery | CRITICAL | 6 | Compiler-friendly code, bailout detection, incremental adoption |
| Bundle & Loading | CRITICAL | 6 | Route splitting, barrel elimination, dynamic imports, prefetching |
| Rendering Optimization | HIGH | 6 | Virtualization, children pattern, debouncing, CSS containment |
| Data Fetching Performance | HIGH | 5 | Waterfall elimination, route preloading, SWR, deduplication |
| Core Web Vitals | MEDIUM-HIGH | 5 | INP yielding, LCP priority, CLS prevention, image optimization |
| State & Subscription Performance | MEDIUM-HIGH | 5 | Context splitting, selectors, atomic state, derived state |
| Profiling & Measurement | MEDIUM | 5 | DevTools profiling, flame charts, CI budgets, production builds |
| Memory Management | LOW-MEDIUM | 5 | Effect cleanup, async cancellation, closure leaks, heap analysis |

## Quick Reference

**Critical patterns** — get these right first:
- Write compiler-friendly components to unlock automatic 2-10x optimization
- Split code at route boundaries to reduce initial bundle by 40-70%
- Eliminate barrel files to enable tree shaking
- Detect and fix silent compiler bailouts

**Common mistakes** — avoid these anti-patterns:
- Reading refs during render (breaks compiler optimization)
- Importing entire libraries when only using one function
- Not profiling before optimizing (targeting the wrong bottleneck)
- Missing effect cleanup (subscription memory leaks)

## Table of Contents

1. [React Compiler Mastery](references/_sections.md#1-react-compiler-mastery) — **CRITICAL**
```
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