Reduce the client bundle size of App Router

[SukkaW]

After migrating a Next.js app from Pages Router to App Router and using as many RSC as possible, I notice that the client js bundle size actually increases by 5%. It turns out that Next.js has introduced a lot of code to the client bundle.

The PR is an attempt to reduce the client bundle size.

[ijjk]

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[shuding]

Thanks! BTW did you measure the diff after this PR?

[SukkaW]

Thanks! BTW did you measure the diff after this PR?

Yeah. But it seems that I can only remove some of the bytes. I am only able to drop a few module imports, which eliminates some Object.defineProperty(t, "__esModule", { value: !0 }) and ("function" == typeof t.default || ("object" == typeof t.default && null !== t.default)) && void 0 === t.default.__esModule && (Object.defineProperty(t.default, "__esModule", { value: !0 }), Object.assign(t.default, t), (e.exports = t.default));.

On the other hand, I do notice that there are some tree-shaking problems. E.g. the whole next/navigation is introduced to my bundle, while I don't use any of the Router API at all. I am going to work on that in my next PR.