We have seen data to suggest that we could have major performance gains in startup of applications using FXML if we use some specialized / clever .class files instead of actually parsing an XML document or binary XML document. This appears particularly true on iOS where processing overhead (particularly in Java on interpreter) is painful. Instead we should look at compiling FXML files into .class files as an optional step in the application build process and loading those, similar to how we handle bss files and such for CSS.