Faster deploys with improved function caching
By Steven Van ·
Vercel now skips re-uploading unchanged functions, cutting build times by 400-600ms on average and up to 5 seconds on larger builds.
Vercel's build step now skips uploading a function's code when that code hasn't changed since the last deployment. Deployment-specific environment variables such as VERCEL_DEPLOYMENT_ID used to be baked into the function payload, which made every deployment look different even when the code was identical; those variables are now injected at runtime instead, so unchanged functions can be recognised and their upload skipped. Vercel says this cuts build times by 400-600ms on average, and by up to 5 seconds on larger builds.
The change applies automatically, with no configuration needed, to Vercel Functions without a framework, and to projects using Python, Go, Ruby, and Rust. Next.js projects will get the same improvement later, according to the announcement