You can see exactly what the React compiler output is by pasting the listed code into the compiler playground: - https://playground.react.dev/#N4Igzg9grgTgxgUx

You can see exactly what the React compiler output is by pasting the listed code into the compiler playground: - https://playground.react.dev/#N4Igzg9grgTgxgUxALhAMygOzgFwJYSYAEAQlDjoQBTBEAmAhjgwDRE4IAeObhAwgBs8cANZEAvslLlKmAAowIABzABKIsAA6xInEKQBCAHQCIAcyoADMhUJEAJMA7dxl1QG5t2okRgIcsMRU3j5EADwARjJ2+DiGALzAjMxGsYbiRPxCoolZwiLiAHwhoRrOOOIl4QD0UbaYxToe2pWY2nqYYDhEeNh+ALYImN3xRFQAblKYUP0RCDDq8YVE40QA1EQAjJ5tmBjY+HYAgkpKVOpaOh1dRADaaBAQbL1wfgxgCABijwC6RKNQD4AJQQdCgiBgVBeAyGPCIAAZmld9N1bhEGDBnn0EO8ECQMX8AcDQeD5lDsYNhmxETsQtcIIYTOZgiATkpNCAkXSUUQHhAACJMBj-IiAhAAWQQ-QgVHO-2Wl1K9MZpgsHL5guYHKRpT8ARgxFoaQQUksAEkwFJHHzXBIdj5xGx7r8ucjOt10TBNcKiRKpTK5UsNFVlcZVSzPd7tfbQnrAhp2Hg4iaiObLQ5gJ7beIY467p6fq6fHGDWMqmFGqUfGEbLJ2FwcPF1Y8OfQhYkNUKMnkcsBoTiPt8IBlqpWqzXosRyk2QJ7W8kGIlI13MphBPlEv3cfiYCOx9XRyEka0QOIgA https://playground.react.dev/#N4Igzg9grgTgxgUxALhAMygOzgFwJY... In this case, it looks like the compiler has hoisted the console logs from the `useMemo` calls out into the main body of the function component, because it considers those to be side effects. So, the logs are still occurring. However, the actual child component output _is_ being memoized as expected.