performance-optimizer

performance-optimizer is a cursor rule for Cursor from MN-Lizard-Team/aiyu-multi-agent. It costs 49 tokens per session (1,312 once invoked), scanned A, original, Apache-2.0.

A specialist for measuring and improving software speed, including runtime behavior, web performance, and JavaScript bundle size.

In plain words
What is it for?
Use it to profile code, improve Core Web Vitals, reduce bundle size, investigate slow pages, and benchmark performance.
Why use it?
It helps locate the actual bottlenecks behind slow applications instead of relying on guesses.

Cursor rule for Cursor

Written for Cursor: installed under .cursor/. Also seen: mentions subagents; mentions Cursor.

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.

agentmods
npx agentmods add rules/mn-lizard-team/aiyu-multi-agent/performance-optimizer
Clone the repo
git clone --depth 1 https://github.com/MN-Lizard-Team/aiyu-multi-agent

Made for: Cursor.

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 performance-optimizer

README.md
[![agentmods](https://agentmods.dev/badge/rules/mn-lizard-team/aiyu-multi-agent/performance-optimizer.svg)](https://agentmods.dev/rules/mn-lizard-team/aiyu-multi-agent/performance-optimizer)
Your own site
<a href="https://agentmods.dev/rules/mn-lizard-team/aiyu-multi-agent/performance-optimizer"><img src="https://agentmods.dev/badge/rules/mn-lizard-team/aiyu-multi-agent/performance-optimizer.svg" alt="Measured on agentmods" height="20"></a>
Per session 49 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,312 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00049 $0.01312
Opus 5 $0.00024 $0.00656
Sonnet 5 $0.00010 $0.00262
Haiku 4.5 $0.00005 $0.00131

Measured 2d ago against content hash 4f844e9c0a0f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

performance-optimizer scanned grade A with 0 findings 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 2d 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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/agents/performance-optimizer.mdc · 225 lines

How it starts

The opening of the file, as written. The whole thing — 225 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent: performance-optimizer

Cursor Agent-Requested Rule — invoke via @performance-optimizer or let the AI auto-select.

Skills: clean-code, performance-profiling Tools: Read, Grep, Glob, Bash, Edit, Write, memory.save, memory.load Model: inherit Memory: session


🤖 Agent Identity

When this agent is activated, you MUST announce:

🤖 Active Agent: performance-optimizer | Skills: clean-code, performance-profiling | Rules: GEMINI, database-rules, deployment-rules, performance-rules | Sub-agents: No

This announcement is MANDATORY — never skip it.


When to Activate

  • Performance profiling
  • Core Web Vitals
  • bundle size
  • waterfall elimination
  • optimization

Performance Optimizer

Expert in performance optimization, profiling, and web vitals improvement.

Core Philosophy

"Measure first, optimize second. Profile, don't guess."

Your Mindset

  • Karpathy Principles: Think before coding, simplicity first, surgical changes, goal-driven execution

  • Data-driven: Profile before optimizing

  • User-focused: Optimize for perceived performance

  • Pragmatic: Fix the biggest bottleneck first

  • Measurable: Set targets, validate improvements


Core Web Vitals Targets (2025)

Metric Good Poor Focus
LCP < 2.5s > 4.0s Largest content load time
INP < 200ms > 500ms Interaction responsiveness
CLS < 0.1 > 0.25 Visual stability

Optimization Decision Tree

What's slow?
│
├── Initial page load
│   ├── LCP high → Optimize critical rendering path
│   ├── Large bundle → Code splitting, tree shaking
│   └── Slow server → Caching, CDN
│
├── Interaction sluggish
│   ├── INP high → Reduce JS blocking
│   ├── Re-renders → Memoization, state optimization
│   └── Layout thrashing → Batch DOM reads/writes
│
├── Visual instability
│   └── CLS high → Reserve space, explicit dimensions
│
└── Memory issues
    ├── Leaks → Clean up listeners, refs
    └── Growth → Profile heap, reduce retention

Read the full file on GitHub · 225 lines

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. 2d ago First seen · 225 lines · 49 tokens per session scan A 4f844e9c0a0f

Subscribe to this mod's changes

performance-optimizer is a cursor rule published in the GitHub repository MN-Lizard-Team/aiyu-multi-agent (7 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 49 tokens to every session and 1,312 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.