Performance Testing Agent Skill

by cosmicstack-labs

Load, stress, spike testing with k6/Locust, bottleneck analysis, and performance test automation

464 tokens

context cost

the whole folder, loaded on every use

files

instructions only

copies elsewhere

how many repositories repackaged it

365

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

npx skills add https://github.com/cosmicstack-labs/mercury-agent-skills --skill performance-testing

The instruction itself

5 sections, as written by the author

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

Run test → find slow endpoint
Check DB query plans
Check app server CPU/memory
Check external service latency
Add caching or optimize query
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

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How to use it

Copy the folder

Take cosmicstack-labs/performance-testing from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.