Chrome Performance Trace Analyzer

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

Workflow

• User uploads a Chrome Performance trace (.json) to the Working Folder

• Use trace_summary to get an overview of the trace

• 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.