flutter-performance-optimizer

flutter-performance-optimizer is a skill for Claude Code, Codex from Desquared/agents-rules-skills. It costs 47 tokens per session (423 once invoked), scanned A, original, MIT.

A performance checklist for Flutter interfaces, which are app screens built with Dart and Flutter. It focuses on reducing slow drawing, unnecessary widget rebuilds, inefficient lists, and memory leaks.

In plain words
What is it for?
Use it when a Flutter interface has jank, slow scrolling, excessive redraws, complex widget trees, or memory problems. It covers list construction, keys, batching requests, debouncing searches, image sizing, and cleanup.
Why use it?
It helps identify why scrolling or animations feel uneven and why screens do more work than necessary. The suggestions target common causes such as missing const widgets, broad state listeners, sequential requests, and uncancelled timers.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when a Flutter interface has jank, slow scrolling, excessive redraws, complex widget trees, or memory problems. It covers list construction, keys, batching requests, debouncing searches, image sizing, and cleanup.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/desquared/agents-rules-skills/flutter-performance-optimizer
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Desquared/agents-rules-skills --skill flutter-performance-optimizer
Clone the repo
git clone --depth 1 https://github.com/Desquared/agents-rules-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for flutter-performance-optimizer

README.md
[![agentmods](https://agentmods.dev/badge/skills/desquared/agents-rules-skills/flutter-performance-optimizer/github.svg)](https://agentmods.dev/skills/desquared/agents-rules-skills/flutter-performance-optimizer)
Your own site
<a href="https://agentmods.dev/skills/desquared/agents-rules-skills/flutter-performance-optimizer"><img src="https://agentmods.dev/badge/skills/desquared/agents-rules-skills/flutter-performance-optimizer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for flutter-performance-optimizer

Your own site · 80×15
<a href="https://agentmods.dev/skills/desquared/agents-rules-skills/flutter-performance-optimizer"><img src="https://agentmods.dev/badge/skills/desquared/agents-rules-skills/flutter-performance-optimizer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 423 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00047 $0.00423
Opus 5.5 $0.00019 $0.00169
Sonnet 5.5 $0.00009 $0.00085
Haiku 4.5 $0.00005 $0.00042

Measured 1mo ago against content hash 54f509407667, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

flutter-performance-optimizer scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

// ❌ for (item in items) await api.fetch(item.id);
skills/flutter-performance-optimizer/SKILL.md · 57 lines

What it actually says

Optimization Skill

Quick Wins

// 1. const: const Text('Title') vs Text('Title')

// 2. Narrow BlocBuilder: Scaffold(body: BlocBuilder(...)) 
//    vs BlocBuilder(builder: (ctx, state) => Scaffold(...))

// 3. buildWhen: buildWhen: (prev, curr) => prev.data != curr.data

// 4. ListView.builder vs ListView(children: [])

// 5. Keys: key: ValueKey(items[i].id)

// 6. Batch API:
// ❌ for (item in items) await api.fetch(item.id);
// ✅ await Future.wait(items.map((i) => api.fetch(i.id)));
// ✅✅ await api.fetchBatch(ids);

// 7. Debounce:
Timer? _debounce;
void onSearchChanged(String q) {
  _debounce?.cancel();
  _debounce = Timer(Duration(milliseconds: 300), () => _search(q));
}

// 8. Heavy work: compute(_heavy, data) in Bloc, NOT in build()

// 9. Images: CachedNetworkImage with width/height

// 10. Memory leaks:
@override Future<void> close() { _controller.close(); return super.close(); }
@override void dispose() { _timer?.cancel(); super.dispose(); }

Common Issues

  • BlocBuilder wraps entire screen → Narrow scope
  • Missing const → Add const
  • No buildWhen → Filter rebuilds
  • ListView without .builder → Use .builder
  • Sequential API calls → Batch or parallel
  • Heavy computation in build() → Move to Bloc/isolate
  • Streams/timers not closed → Dispose properly

Diagnostics

flutter run --profile --trace-skia
# DevTools → Memory, Performance
Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 57 lines · 47 tokens per session scan A 54f509407667

Subscribe to this mod's changes

flutter-performance-optimizer is a skill published in the GitHub repository Desquared/agents-rules-skills (4 stars, last pushed 17d ago), licensed MIT. It adds 47 tokens to every session and 423 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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