Summary
Cloudflare added Worker startup profiling to Wrangler: wrangler check startup now reports raw and compressed bundle sizes plus a CPU activity summary and generates a .cpuprofile file for flamegraph analysis in Chrome DevTools, available in Wrangler 4.116.0 and later.
What changed
wrangler check startup now surfaces raw and compressed bundle sizes and a CPU activity summary, and emits a .cpuprofile file that can be loaded as a flamegraph in Chrome DevTools, shipping in Wrangler 4.116.0+.
Why it matters
Worker startup time directly affects cold-start latency for edge-hosted agents and APIs, so built-in bundle-size and CPU profiling gives developers a first-party way to diagnose and cut initialization cost without external tooling.
Evidence excerpt
wrangler check startup now reports raw and compressed bundle sizes plus a CPU activity summary, and generates a .cpuprofile file for detailed flamegraph analysis in Chrome DevTools. Available in Wrangler 4.116.0+.