This is exactly my same problem. My app (and applet) is about 5 MB if I consider all the classes and libraries used by the app. (I mean 5MB is the size of the jar file). I can't ask customers to download 5 MB every time they want to access the program.
We need java ask code signing for the principal applet but then we must have the possibility to run single class files as needed.
Help us all please.