Do I need to memoize selectors?

[mfbx9da4]

It is generally recommended to memoize selectors with useCallback.

Is it generally recommended to memoize all selectors? Seems like a premature optimisation for the most part?

If it's not a premature optimization seems like a major omission to exclude factories from the zustand library. Will it be death by a thousand cuts?

If most of the time it is a premature optimisation, under what circumstances is it advised?

[dai-shi]

That section is introduced in v3, because at that time we were expecting useMutableSource which would require memoized selectors (without stable selectors, it caused infinite loop). #422

Now, we will have useSyncExternalStore instead and memoized selectors are not necessary. That section is removed in v4. #550 (Hmm, we can remove it now, but v4 will probably be released any time soon.)

[mfbx9da4]

Thanks for the response. Sounds like there are no performance considerations wrt necessity of memoising selectors. Could you confirm this please?

[dai-shi]

In the current implementation, having a stable selector will skip invoking the selector, so it's technically efficient to define a selector outside component. But, yes, it's premature optimization and will not be noticeable in practice.