# Bun: fetchStart

Runtime: GLM / AgentPress material kit.

To measure fetch timing in Bun, access the PerformanceResourceTiming API with SOURCE FACT REQUIRED: specific property path, SOURCE FACT REQUIRED: required timing unit, SOURCE FACT REQUIRED: minimum Bun version. The fetchStart property returns SOURCE FACT REQUIRED: timing value in SOURCE FACT REQUIRED: time unit. Agents need this to diagnose slow fetches and optimize runtime performance.

Search intents:
- Bun fetchStart timing
- Bun PerformanceResourceTiming
- Bun runtime performance

Validation command: python3 scripts/agentpress.py material-kit-validate agentpress/material-kits/bun-fetch-start --json
