Performance Regression Debugging

When your app suddenly slows down after a deployment, this walks you through comparing baseline metrics against current performance, identifying what changed, and fixing it. It covers the full cycle: detecting regressions through measurement (response times, memory usage, bundle size), profiling to find the root cause, verifying your fixes actually work, and setting up prevention so it doesn't happen again. The approach is systematic rather than guessing. You get reference guides for each phase plus patterns for continuous monitoring. Best used when you have metrics showing degradation and need a structured debugging process rather than ad hoc investigation.

skills.sh installs: 449
GitHub stars: 379
last updated: Aug 21, 2026

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Install

$ npx -y skills add aj-geddes/useful-ai-prompts --skill performance-regression-debugging --agent claude-code

Installs into .claude/skills of the current project.

Files

Overview

Performance regressions occur when code changes degrade application performance. Detection and quick resolution are critical.

When to Use

After deployment performance degrades
Metrics show negative trend
User complaints about slowness
A/B testing shows variance
Regular performance monitoring

Quick Start

Minimal working example:

// Before: 500ms response time
// After: 1000ms response time (2x slower = regression)

// Capture baseline metrics
const baseline = {
  responseTime: 500, // ms
  timeToInteractive: 2000, // ms
  largestContentfulPaint: 1500, // ms
  memoryUsage: 50, // MB
  bundleSize: 150, // KB gzipped
};

// Monitor after change
const current = {
  responseTime: 1000,
  timeToInteractive: 4000,
  largestContentfulPaint: 3000,
  memoryUsage: 150,
  bundleSize: 200,
};

SKILL.md on GitHub