performance

performance is a skill for Claude Code, Codex from eaescob/resiliency_skills. It costs 84 tokens per session (1,175 once invoked), scanned A, original, Apache-2.0.

A performance testing and optimization guide for web applications. It covers load tests, stress tests, soak tests, benchmarks, and profiling for Next.js, Express, React, and Go.

In plain words
What is it for?
Use it to test expected traffic, find an application's breaking point, compare implementations, check long-running behavior, and set response-time or error-rate targets with tools such as k6.
Why use it?
It helps reveal slow responses, capacity limits, memory leaks, and regressions before they affect production users.

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/eaescob/resiliency_skills/performance
Any agent
npx skills add eaescob/resiliency_skills --skill performance
Clone the repo
git clone --depth 1 https://github.com/eaescob/resiliency_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 performance

README.md
[![agentmods](https://agentmods.dev/badge/skills/eaescob/resiliency_skills/performance.svg)](https://agentmods.dev/skills/eaescob/resiliency_skills/performance)
Your own site
<a href="https://agentmods.dev/skills/eaescob/resiliency_skills/performance"><img src="https://agentmods.dev/badge/skills/eaescob/resiliency_skills/performance.svg" alt="Measured on agentmods" height="20"></a>
Per session 84 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,175 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 $0.00084 $0.01175
Opus 5 $0.00042 $0.00588
Sonnet 5 $0.00017 $0.00235
Haiku 4.5 $0.00008 $0.00118

Measured 4d ago against content hash c13ad4d76d2d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

performance 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 4d 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.

skills/performance/SKILL.md · 166 lines

How it starts

The opening of the file, as written. The whole thing — 166 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Performance Testing

Implement load testing, benchmarking, and performance profiling.

Testing Types

Type Purpose When to Use
Load Test Validate expected traffic Before launch, after changes
Stress Test Find breaking point Capacity planning
Soak Test Find memory leaks Before major releases
Benchmark Compare implementations During optimization

Quick Start

Load Testing with k6

# Install k6
brew install k6  # macOS
# or: https://k6.io/docs/getting-started/installation/

# Run basic test
k6 run load-test.js

Basic load test script:

// load-test.js
import http from "k6/http"
import { check, sleep } from "k6"

export const options = {
  stages: [
    { duration: "30s", target: 20 },  // Ramp up
    { duration: "1m", target: 20 },   // Stay at 20 users
    { duration: "10s", target: 0 },   // Ramp down
  ],
  thresholds: {
    http_req_duration: ["p(95)<500"], // 95% under 500ms
    http_req_failed: ["rate<0.01"],   // <1% errors
  },
}

export default function () {
  const res = http.get("http://localhost:3000/api/health")
  check(res, {
    "status is 200": (r) => r.status === 200,
    "response time < 200ms": (r) => r.timings.duration < 200,
  })
  sleep(1)
}

Reference Guides

Load Testing

See references/load-testing.md for:

  • k6 advanced configuration
  • Testing authenticated endpoints
  • CI/CD integration

Benchmarking

See references/benchmarking.md for:

  • Node.js benchmarking
  • Go benchmarking
  • Database query benchmarking

Profiling

See references/profiling.md for:

  • Node.js profiling (clinic.js, 0x)
  • Go profiling (pprof)
  • Memory leak detection

Performance Budgets

Set and enforce performance targets:

Metric Target Critical
Time to First Byte (TTFB) < 200ms < 600ms
First Contentful Paint (FCP) < 1.8s < 3s
Largest Contentful Paint (LCP) < 2.5s < 4s
Cumulative Layout Shift (CLS) < 0.1 < 0.25
API Response Time (p95) < 500ms < 1000ms
Error Rate < 0.1% < 1%

Read the full file on GitHub · 166 lines

Files

What ships with it

3 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. 4d ago First seen · 166 lines · 84 tokens per session scan A c13ad4d76d2d

Subscribe to this mod's changes

performance is a skill published in the GitHub repository eaescob/resiliency_skills (2 stars, last pushed 7mo ago), licensed Apache-2.0. It adds 84 tokens to every session and 1,175 once invoked, about $0.0004 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 2026-08-31.

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