Note that when using sass (Dart Sass), synchronous compilation is twice as fast as asynchronous compilation by default, due to the overhead of asynchronous callbacks.

This is a very dangerous practice as each optimization means making assumptions. If you are compressing an image you make an assumption that some payload can be cut out without seriously affecting the quality, if you are adding a cache to your backend you assume that the API will return same results. A correct assumption allows you to spare resources. A false assumption introduces a bug in your app. That’s why optimizations should be done consciously.

In the vast majority of cases there’s nothing wrong about wasted renders. They take so little resources that it is simply undetectable for a human eye. In fact, comparing each component’s props to its previous props shallowly (I’m not even talking about deeply) can be more resource extensive then simply re-rendering the entire subtree.

Performance optimizations are not free. They ALWAYS come with a cost but do NOT always come with a benefit to offset that cost.

Even having useCallback() returning the same function instance, it doesn’t bring any benefits because the optimization costs more than not having the optimization.