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Comment by clementmas | Hacker News Reader

That kind of performance optimization should be applied automatically. It's a welcomed addition for advanced developers but it should be the machine's job.

I think frameworks like SolidJS or Svelte are one step ahead in that regards. As far as I understand, they can surgically update the DOM without having to re-render the whole component. I wonder if Vue 4 will still use a Virtual DOM.

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Just piping everything through a memo function can end up with worse performance than before.

Memoization tends to work better as a manual fine-tune, when everything about how the data is created, updated and used is understood beforehand.

Speaking from a React perspective at least, I think it's not the default because technically nothing stops someone from writing really smelly, non-idiomatic code where memoizing it could cause logic errors. At the very least it would be a breaking API change

I'm with you, I think catering to those cases is a fool's errand, but I understand the argument for doing it.

If the machine could do it you wouldn't need to use a directive for it. It's not like Vue is doing no optimization at all behind the scenes; there's just only so much you can do that will still allow the developer to maintain 100% confidence in the framework.

That's exactly what Vue does (unlike say React). Only those parts of the VDOM are updated whose dependencies changed. v-memo is mostly for lists and cases where updates should be delayed for reasons like flickering.

Vue already tracks dependencies. V-memo is a special case where they want to react to values which are determined by user, instead of all react values used(default for Vue) .

Memoization costs memory. Better add it where it counts. Disabling it afterwards when your app has run out of memory will be painful.

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