JavaFX2 - very poor performance when adding custom made (fxml)panels to gridpane dynamically

Question

Problem I want to add custom made panels, built via javafx scene builder, to a gridpane at runtime. My custom made panel exsits of buttons, labels and so on

Answer 1

Just adding code for "caching of already loaded classes" in @Sebastian sir given code. It is working for me. Please suggest changes in it for better performance.

@Override
public Class loadClass(String name) throws ClassNotFoundException {
    System.out.println("In Class loader");

    Class result;
    System.out.println(" >>>>>> Load class : "+name);
    result = (Class)classes.get(name);
    if(result != null){
        System.out.println(" >>>>>> returning cached class.");
        return result;
    }else{
    Class c = findClass(name);
    if ( c == null ) {
      throw new ClassNotFoundException( name );
    }
    System.out.println(" >>>>>> loading new class for first time only");
    return c;
    }
}