When zod v3 is used in a CommonJS codebase that uses esbuild, rollup or webpack to package and minify code, the bundle size contribution of zod is ~68K which is pretty good. When v4 or v4-mini is used, the bundle size contribution increases more than 4x with the same project setup.

I've done some experiments with different bundlers and different versions of zod and here are some results:

This is a fairly major increase for anyone using this fairly common project setup (not just for front-end bundles — anyone using something like AWS Lambda will get slower cold starts due to the increased bundle size).