While not exclusively about internals, performance is inextricably linked to how the system works behind the scenes. A thorough book on the topic, also authored by Jorge Castillo, is "Jetpack Compose Performance."
Press Ctrl + P (Windows/Linux) or Cmd + P (Mac) in your web browser. Select from the destination menu. jetpack compose internals pdf download
A Composable that can act as an entry point for recomposition. If its state changes, Compose can re-run this specific function without restarting the entire parent scope. While not exclusively about internals
Where to place it. Compose measures and positions each node in the UI tree. also authored by Jorge Castillo