performance-testing

performance-testing is a skill for Claude Code, Codex from cosmicstack-labs/mercury-agent-skills. It costs 24 tokens per session (504 once invoked), scanned A, original, MIT.

A guide to performance testing, which measures how software behaves under normal, heavy, sudden, or sustained traffic. It covers load, stress, spike, endurance, and soak tests using tools such as k6 and Locust.

In plain words
What is it for?
Use it to design load tests, find bottlenecks, check breaking points, and automate performance checks.
Why use it?
It helps reveal slow responses, capacity limits, and memory leaks before users encounter them in production.

Skill for Claude CodeCodex

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

Good fit Use it to design load tests, find bottlenecks, check breaking points, and automate performance checks.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/cosmicstack-labs/mercury-agent-skills/performance-testing
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 cosmicstack-labs/mercury-agent-skills --skill performance-testing
Clone the repo
git clone --depth 1 https://github.com/cosmicstack-labs/mercury-agent-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-testing

README.md
[![agentmods](https://agentmods.dev/badge/skills/cosmicstack-labs/mercury-agent-skills/performance-testing/github.svg)](https://agentmods.dev/skills/cosmicstack-labs/mercury-agent-skills/performance-testing)
Your own site
<a href="https://agentmods.dev/skills/cosmicstack-labs/mercury-agent-skills/performance-testing"><img src="https://agentmods.dev/badge/skills/cosmicstack-labs/mercury-agent-skills/performance-testing/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 performance-testing

Your own site · 80×15
<a href="https://agentmods.dev/skills/cosmicstack-labs/mercury-agent-skills/performance-testing"><img src="https://agentmods.dev/badge/skills/cosmicstack-labs/mercury-agent-skills/performance-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 504 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Data Exfiltration · line 45
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
How audits are shown
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 $0.00024 $0.00504
Opus 5 $0.00012 $0.00252
Sonnet 5 $0.00005 $0.00101
Haiku 4.5 $0.00002 $0.00050

Measured 8d ago against content hash d7f07450e6fa, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

performance-testing 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 8d 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.

categories/testing-qa/performance-testing/SKILL.md · 67 lines

What it actually says

Performance Testing

Load, stress, and spike test your systems to ensure reliability at scale.

Types of Performance Tests

Type Goal Pattern
Smoke Verify basic perf with minimal load 1-5 users for 1 min
Load Test under expected traffic Ramp to target, hold 10-30 min
Stress Find breaking point Ramp up until failure
Spike Handle sudden traffic bursts Instant 10x load for 2-5 min
Endurance Detect memory leaks over time Sustained load for 1-24 hrs
Soak Verify long-term stability 50% load for hours

k6 Patterns

import http from 'k6/http';
import { check, sleep } from 'k6';

export const options = {
  stages: [
    { duration: '2m', target: 100 },  // Ramp up
    { duration: '5m', target: 100 },  // Hold
    { duration: '1m', target: 0 },    // Ramp down
  ],
  thresholds: {
    http_req_duration: ['p(95)<500'],
    http_req_failed: ['rate<0.01'],
  },
};

export default function () {
  const res = http.get('https://api.example.com/users');
  check(res, {
    'status is 200': (r) => r.status === 200,
    'response time < 300ms': (r) => r.timings.duration < 300,
  });
  sleep(1);
}

Bottleneck Analysis Flow

  1. Run test → find slow endpoint
  2. Check DB query plans
  3. Check app server CPU/memory
  4. Check external service latency
  5. Add caching or optimize query
  6. Re-test to verify improvement

Automation

  • Run smoke tests on every PR
  • Run full perf suite nightly
  • Alert on threshold breaches
  • Track latency percentiles over time in dashboards
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. 8d ago First seen · 67 lines · 24 tokens per session scan A d7f07450e6fa

Subscribe to this mod's changes

performance-testing is a skill published in the GitHub repository cosmicstack-labs/mercury-agent-skills (471 stars, last pushed 17d ago), licensed MIT. It adds 24 tokens to every session and 504 once invoked, about $0.0001 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.

Related

Other skills, from other repositories

test-driven-development

Drives development with tests using the red-green-refactor loop. Use when implementing any logic, fixing any bug, or changing any behavior. Use when you need to prove that code works, when a bug report arrives, or when you're about to modify existing functionality.

addyosmani/agent-skills · 57 tokens

skillshare-implement-feature

Implement a feature from a spec file or description using TDD workflow. Use this skill whenever the user asks to: add a new CLI command, implement a feature from a spec, build new functionality, add a flag, create a new internal package, or write Go code for skillshare. This skill enforces test-first development…

runkids/skillshare · 114 tokens

create-custom-grader

Use when converting an existing benchmark, rubric, verifier, task YAML/JSON, or domain check into SkillEvaluator BYOG/BYOT custom evaluation.

NVIDIA/SkillEvaluator · 35 tokens

story-origin-check

Recover the first public timestamp and canonical major coverage for a newsjacking signal, then decide whether newer coverage is the same story, a different story, or a materially new development.

elvisun/newsjack · 40 tokens

prompt-proximity-architecture

Turn an approved measurement charter, ICPs, and buyer jobs into a budget-aware prompt coverage blueprint across proximity bands, aided status, information acts, journey states, roles, locales, evidence grades, partitions, and measurement lanes. Use before prompt wording to define required, optional, and prohibited…

elvisun/newsjack · 67 tokens

xdto-validate

A validator for XDTO packages in 1C:Enterprise. It checks the package model, its metadata object, and its connection to the configuration.

Nikolay-Shirokov/cc-1c-skills · 34 tokens