ViteJS lib 1/3 bigger than esbuild lib

[peterpeterparker]

I'm trying to migrate a library I build with esbuild to vitejs lib but, the resulting bundle is 1/3 bigger with Vitejs.

Anyone has an idea what can be the root cause and if there are parameters I can try to reduce this issue. I know it's Rollup under the hood but, still, 1/3 seems a lot.

When I compare both bundle with their source maps, it seems that every dependency gets bundle with a bit a bigger size which leas the size to grow. Roughly from 260kb to 400kb (non gzipped).

esbuild:

https://github.com/buildwithjuno/juno-js

esbuild
    .build({
      entryPoints,
      outdir: 'dist/esm',
      bundle: true,
      sourcemap: true,
      minify: true,
      splitting: true,
      format: 'esm',
      define: {global: 'window'},
      target: ['esnext'],
      plugins: [NodeModulesPolyfillPlugin()]
    })
    .catch(() => process.exit(1));

vitejs:

junobuild/juno-js#6

export default defineConfig({
    build: {
      lib: {
        entry: resolve(process.cwd(), 'src/index.ts'),
        name,
        fileName: 'index'
      },
      sourcemap: true
    }
});

Source maps

esbuild:

vitejs: