Extract to Memoized Components
Extract expensive work into memoized components to enable early returns before computation.
Incorrect (computes avatar even when loading):
function Profile({ user, loading }: Props) {
const avatar = useMemo(() => {
const id = computeAvatarId(user)
return <Avatar id={id} />
}, [user])
if (loading) return <Skeleton />
return <div>{avatar}</div>
}Correct (skips computation when loading):
const UserAvatar = memo(function UserAvatar({ user }: { user: User }) {
const id = useMemo(() => computeAvatarId(user), [user])
return <Avatar id={id} />
})
function Profile({ user, loading }: Props) {
if (loading) return <Skeleton />
return (
<div>
<UserAvatar user={user} />
</div>
)
}Note: If your project has React Compiler enabled, manual memoization with memo() and useMemo() is not necessary. The compiler automatically optimizes re-renders.