performance-testing

name	performance-testing
description	Web Vitals and load time testing patterns with Playwright. Use when measuring Core Web Vitals (LCP, FID, CLS), setting performance budgets, analyzing network performance, or profiling resource loading times.

Performance Testing Skill

Best practices for performance testing with Playwright to ensure your application meets performance requirements.

Why Performance Testing

• User experience - Slow pages lead to user frustration and abandonment
• SEO impact - Page speed affects search rankings
• Business metrics - Performance correlates with conversion rates
• Early detection - Catch performance regressions before production

Table of Contents

• Web Vitals Measurement
• Network Performance
• Resource Loading
• Performance Assertions
• Performance Budgets
• Profiling and Tracing

---

Web Vitals Measurement

Core Web Vitals

import { test, expect } from '@playwright/test';

test('measure Core Web Vitals', async ({ page }) => {
  // Enable performance observer before navigation
  await page.addInitScript(() => {
    . = {};

    
     ( {
       entries = list.();
       lastEntry = entries[entries. - ];
      .. = lastEntry.;
    }).({ : , :  });

    
     ( {
       entries = list.();
      .. = entries[]. - entries[].;
    }).({ : , :  });

    
     clsValue = ;
     ( {
       ( entry  list.()) {
         (!entry.) {
          clsValue += entry.;
        }
      }
      .. = clsValue;
    }).({ : , :  });
  });

   page.();
   page.();

  
   page.();

   metrics =  page.( .);

  
  (metrics.).(); 
  (metrics.).(); 
});