https://sanjaydevtech.medium.com/jetpack-compose-internals-part-1-performance-732f24c07f36

MainActivity.kt

// import ....
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
import androidx.compose.material3.Text
import androidx.compose.material3.TextField
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp

// UI State
data class UIState(val name: String, val title: String)

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MyApplicationTheme {
                Surface(modifier = Modifier.fillMaxSize(), color = MaterialTheme.colorScheme.background) {
                    EditUI() // <-- Called EditUI
                }
            }
        }
    }
}

@Composable
fun EditUI() {
    var uiState by remember {
        mutableStateOf(UIState("", ""))
    }
    Column(
        modifier = Modifier.padding(horizontal = 16.dp)
    ) {
        TextField(
            modifier = Modifier.fillMaxWidth(),
            value = uiState.name, onValueChange = {
                uiState = uiState.copy(name = it) // <-- Trigger recomposition
            }, placeholder = {
                Text(text = "Name")
            })
        TextField(
            modifier = Modifier.fillMaxWidth(),
            value = uiState.title, onValueChange = {
                uiState = uiState.copy(title = it) // <-- Trigger recomposition
            }, placeholder = {
                Text(text = "Title")
            })
        DisplayUI(uiState)
    }
}

@Composable
fun DisplayUI(uiState: UIState) {
    Column {
        Text(text = uiState.name)
        Text(text = uiState.title)
    }
}