# flutter-performance

> Claude/Codex skill by [@zakariaf](https://omgskills.com/library/zakariaf/index.md) · 61 stars · Updated 2026-09-23

Enforces Flutter runtime performance — const subtrees, minimal rebuild scope via ref.watch(select), lazy ListView/GridView builders and slivers, sized image decode (cacheWidth/ResizeImage), heavy work off the UI isolate via compute/Isolate, surgical RepaintBoundary, dispose everything, and measurement in profile mode on a floor device. Use when optimizing UI, diagnosing jank or dropped frames, tuning long lists or images, reviewing rebuild/repaint scope, or when the task mentions const, select, ListView.builder, cacheWidth, compute, RepaintBoundary, AnimatedBuilder, DevTools, raster thread, or 60/120fps.

Tags: agent-skills, ai-agents, best-practices, claude-code, codex, coding-agent, cursor, dart, dartlang, developer-tools, drift, flutter, flutter-architecture, github-copilot, go-router, llm, material-design, mvvm, riverpod, skills

## Install

```sh
git clone https://github.com/zakariaf/Flutter-Skills /tmp/Flutter-Skills && ln -s /tmp/Flutter-Skills/skills/flutter-performance ~/.claude/skills/flutter-performance
```

## From README

Flutter Performance Hold a steady 60 fps ( s.field). A HUD counter tick must never rebuild a heavy sibling. Rebuild scope is the single biggest lever on build-thread cost. Lazy everything long. ListView.builder / GridView.builder / slivers for variable or unbounded content. ListView(children: items.map(...).toList()) builds every off-screen row up front — refuse it for anything not tiny and fixed. No expensive work in build(). No jsonDecode, sort, regex, DateTime math, file/network, or large allocation — build() may run every frame. Compute in the Notifier/ViewModel once and cache the result in immutable state. Heavy CPU off the UI isolate. Parse large payloads, process images, crunch numbers in compute() or a spawned Isolate. Blocking the UI thread is guaranteed jank; the raster thread cannot save you. Size image decode to the display slot. cacheWidth/cacheHeight or ResizeImage, correct asset resolutions, precacheImage for above-the-fold art.

## Links

- HTML page: https://omgskills.com/library/zakariaf/flutter-skills/skills/flutter-performance/
- GitHub: https://github.com/zakariaf/Flutter-Skills
- Author: [@zakariaf](https://omgskills.com/library/zakariaf/index.md)

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