How to reduce the number of recompositions in an application besides using side effects?

Use remember.

Apply stable data types (marked with @Stable or @Immutable).

Delegate calculations:

// Avoid recalculations on every recomposition
val myExpensiveValue by remember {
    derivedStateOf {
        calculateExpensiveValue()
    }
}

Use lambdas that capture the minimum number of variables:

// Lambda will be recreated only when count changes
Button(onClick = { onCountChanged(count + 1) }) {
    Text("Increment")
}

Apply Composable functions with the minimum number of parameters.

Use Composable with @MovableContentOf if you need to move a subtree of Compose without recomposition.

Use composite keys (key) for lists if more precise matching of elements is required during changes.

Avoid calling non-stable functions within a Composable.