How to Use the Performance Tab in Chrome DevTools

· Category: VS Code & Developer Tools

Short answer

The Performance tab records CPU usage, rendering frames, and network activity over time. It helps identify slow scripts, layout thrashing, and long tasks.

Steps

  1. Open DevTools and navigate to the Performance tab.
  2. Click the record button, interact with the page, then stop recording.
  3. Review the timeline for long yellow blocks indicating JavaScript execution.
  4. Zoom into frames to see detailed function call stacks.
  5. Look for red triangles indicating forced synchronous layout.

Tips

  • Enable the Screenshots checkbox to see visual state changes.
  • Use the Bottom-Up view to find which functions consumed the most time.
  • Record in Incognito mode to avoid extension interference.

Common issues

  • Profiling adds overhead, so absolute times may differ from production.
  • Very long recordings become hard to navigate; focus on specific interactions.