Chrome Performance Trace Analyzer

Analyze Chrome DevTools Performance trace JSON exports to answer questions about network requests, timing, and performance bottlenecks.

Workflow

1. User uploads a Chrome Performance trace (.json) to the Working Folder
2. Use trace_summary to get an overview of the trace
3. Use specific tools to investigate:
   • trace_network - All network requests
   • trace_network_window - Network requests in a time range
   • trace_long_tasks - Main thread blocking tasks
   • trace_slowest - Slowest events overall
   • trace_filter - Custom filtering

Common Questions

User Question	Tool to Use
"What network calls happened between 2-5 seconds?"	trace_network_window(start_ms=2000, end_ms=5000)
"What took the most time?"	trace_slowest(count=10)
"Are there any long tasks?"	trace_long_tasks(threshold_ms=50)
"Show me JavaScript execution issues"	trace_filter(category="v8")
"What's in this trace?"	trace_summary()

Time Units

• All times are in milliseconds relative to trace start
• Use trace_summary to get total trace duration
• Network request times show when the request started and its duration

Key Metrics to Look For

Long Tasks (>50ms)

Tasks that block the main thread for more than 50ms cause jank and poor interactivity.

Slow Network Requests

Requests taking >500ms may indicate:

• Server issues (high TTFB)
• Large payloads
• Missing caching

Layout Thrashing

Frequent Layout events in a short window indicate forced synchronous layouts.

JavaScript Execution

Look for long v8.execute or FunctionCall events.

Reference

For trace event format details, load the trace_format resource.