On Vercel, the Vercel Flags SDK now initializes faster on cold starts, and usage reporting no longer keeps functions running after the response.
Copy link to headingFaster cold starts
Two changes speed up SDK initialization on cold starts:
The SDK loads and parses the flags datafile bundled with your deployment as soon as the client is created, so it’s ready before your code evaluates its first flag.
Every function invocation now includes the current datafile revision, so the SDK can check whether the bundled datafile is up to date without a network request.
In internal testing, eliminating the network wait reduced p75 cold-start SDK initialization time from over 70 ms to 10 ms, roughly 7x faster.
After initialization, flag reads are effectively instant. Across cold and warm invocations, p99 flag-read latency is under 1 ms.
Copy link to headingUsage reporting no longer extends function duration
The SDK previously used waitUntil for usage reporting, keeping functions running after the response was sent. It now passes usage events to the Vercel runtime, so reporting no longer adds to function duration.
Update @flags-sdk/vercel to version 1.5.3 or later and redeploy your application:
pnpm add @flags-sdk/vercel@latestLearn more in the Flags SDK documentation.