How can I mark LocalDate, LocalDateTime and LocalTime immutable so compose can skip them when they haven't changed？

You have to either create a wrapper over those, like this:

@Stable
data class StableHolder<T>(val value: T)

fun <T : Any> T.wrapAsStable(): StableHolder<T> {
    return StableHolder(this)
}

Thank you.

Agree, there is quite a big topic around that at google bugtracker

Yeah, or they’d need to somehow be convinced to have more such 3rd party objects marked as stable by them. Like they did with

kotlinx.collections.immutable.ImmutableList

and so on. But either way, I don’t see that happening very soon.