performance-engineer

performance-engineer is a skill for Claude Code, Codex from zhaono1/agent-playbook. It costs 23 tokens per session (1,361 once invoked), scanned A, original, MIT.

A workflow for finding and improving application performance, meaning how quickly and efficiently software responds and uses resources.

In plain words
What is it for?
Use it when an application is slow, has high latency, or needs efficiency improvements. It helps define targets, measure current behaviour, profile code, and investigate likely bottlenecks.
Why use it?
It replaces assumptions about slowness with measurements, profiling, and bottleneck analysis. Bottlenecks can occur in databases, APIs, application code, frontends, or networks.

Skill for Claude CodeCodex

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 skills/zhaono1/agent-playbook/performance-engineer
Any agent
npx skills add zhaono1/agent-playbook --skill performance-engineer
Clone the repo
git clone --depth 1 https://github.com/zhaono1/agent-playbook

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 performance-engineer

README.md
[![agentmods](https://agentmods.dev/badge/skills/zhaono1/agent-playbook/performance-engineer.svg)](https://agentmods.dev/skills/zhaono1/agent-playbook/performance-engineer)
Your own site
<a href="https://agentmods.dev/skills/zhaono1/agent-playbook/performance-engineer"><img src="https://agentmods.dev/badge/skills/zhaono1/agent-playbook/performance-engineer.svg" alt="Measured on agentmods" height="20"></a>
Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,361 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00023 $0.01361
Opus 5 $0.00012 $0.00681
Sonnet 5 $0.00005 $0.00272
Haiku 4.5 $0.00002 $0.00136

Measured 5d ago against content hash de4520288e73, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

performance-engineer 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 5d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/perf_report.py, scripts/profile.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

curl -w "@curl-format.txt" -o /dev/null -s https://example.com/users
skills/performance-engineer/SKILL.md · 251 lines

How it starts

The opening of the file, as written. The whole thing — 251 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Performance Engineer

Specialist in analyzing and optimizing application performance, identifying bottlenecks, and implementing efficiency improvements.

When This Skill Activates

Activates when you:

  • Report performance issues
  • Need performance optimization
  • Mention "slow" or "latency"
  • Want to improve efficiency

Performance Analysis Process

Phase 1: Identify the Problem

  1. Define metrics

    • What's the baseline?
    • What's the target?
    • What's acceptable?
  2. Measure current performance

    # Response time
    curl -w "@curl-format.txt" -o /dev/null -s https://example.com/users
    
    # Database query time
    # Add timing logs to queries
    
    # Memory usage
    # Use profiler
    
  3. Profile the application

    # Node.js
    node --prof app.js
    
    # Python
    python -m cProfile app.py
    
    # Go
    go test -cpuprofile=cpu.prof
    

Phase 2: Find the Bottleneck

Common bottleneck locations:

Layer Common Issues
Database N+1 queries, missing indexes, large result sets
API Over-fetching, no caching, serial requests
Application Inefficient algorithms, excessive logging
Frontend Large bundles, re-renders, no lazy loading
Network Too many requests, large payloads, no compression

Phase 3: Optimize

Database Optimization

N+1 Queries:

// Bad: N+1 queries
const users = await User.findAll();
for (const user of users) {
  user.posts = await Post.findAll({ where: { userId: user.id } });
}

// Good: Eager loading
const users = await User.findAll({
  include: [{ model: Post, as: 'posts' }]
});

Missing Indexes:

-- Add index on frequently queried columns
CREATE INDEX idx_user_email ON users(email);
CREATE INDEX idx_post_user_id ON posts(user_id);
API Optimization

Pagination:

// Always paginate large result sets
const users = await User.findAll({
  limit: 100,
  offset: page * 100
});

Read the full file on GitHub · 251 lines

Files

What ships with it

6 files 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. 5d ago First seen · 251 lines · 23 tokens per session scan A de4520288e73

Subscribe to this mod's changes

performance-engineer is a skill published in the GitHub repository zhaono1/agent-playbook (77 stars, last pushed 10d ago), licensed MIT. It adds 23 tokens to every session and 1,361 once invoked, about $0.0001 per session on Opus 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 2026-08-30.

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