Function uploads are now skipped when code hasn't changed, reducing build times by 400-600ms on average and up to 5 seconds for larger builds. Previously, deployment-specific environment variables like were included in the function payload, making every deployment unique even with identical code. These variables are now injected at runtime, allowing Vercel to recognize unchanged functions and skip redundant uploads.VERCEL_DEPLOYMENT_ID This optimization applies to without a framework, and projects using Python, Go, Ruby, and Rust.

Next.js projects will receive the same improvement soon.Vercel Functions The optimization is applied automatically to all deployments with no configuration required. Learn more about and in our documentation.functionsbuilds Read more