---

name: browser-required description: "Use when auditing slow page loads, heavy assets, or rendering delays related to Perform browser-based performance audits. Verify the actual bottleneck in DevTools, Lighthouse, or field data before recommending changes." metadata: category: performance priority: medium difficulty: intermediate estimatedTime: "10" source: frontendchecklist.io url: https://frontendchecklist.io/rules/performance/browser-required

Perform browser-based performance audits

Static analysis alone cannot simulate the complex rendering, script execution, and layout processes of modern web browsers, which is essential for capturing real-world performance.

Quick Reference

• Use real browser engines to capture runtime metrics (LCP, CLS, INP)
• Synthetic tests in full browsers reveal execution bottlenecks
• Verify performance across different device and connection simulations

Check

Ensure that performance audits are conducted in an environment that executes JavaScript and renders the page (e.g., Lighthouse, Puppeteer).

Fix

Integrate browser-based testing tools like Lighthouse or WebPageTest into the development workflow and CI/CD pipeline.

Explain

Explain the limitations of static analysis for performance and why a full browser environment is necessary.

Code Review

Review the routes, assets, and loading behavior that affect Perform browser-based performance audits. Flag exact files, requests, or rendering steps that add unnecessary network, CPU, or layout cost, and describe the measurement method used to confirm the issue.

---

For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/rules/performance/browser-required