Vercel's October 29 changelog describes two changes to the Vercel Flags SDK: faster initialization on cold starts and usage reporting that no longer keeps a function running after the response.

What changed

  • The SDK loads the deployment's bundled flag datafile when the client is created.
  • A revision included with each invocation lets the SDK check freshness without an additional network request.
  • Vercel reports a drop from more than 70 milliseconds to 10 milliseconds at p75 in internal tests, and recommends version 1.5.3 or later.

These are vendor-reported measurements, not a guarantee for every app or region. The changelog also says flag reads are below one millisecond at p99 across its tested cold and warm invocations.

If the SDK is on a critical path, compare your own cold-start metrics after upgrading and redeploying.