Still shallow. We usually recommend avoiding deep checks because (a) the concept of deep equality is pretty nebulous and hard to design in a predictable, prec

Still shallow. We usually recommend avoiding deep checks because (a) the concept of deep equality is pretty nebulous and hard to design in a predictable, precise way, and (b) deep equality checking can be slow, often just as slow (or slower) than the actual rerender – in which case the memoization is only hurting you. (If you want to do deep equality anyway, you can pass a second argument to React.memo to specify a custom comparator.)