When does internal routines load?

If I have a large procedure or class with many internal routines, is the whole r-code file loaded into memory at once when I instantiate the program, or does it only load the main block and then load the internal routines as needed?

Further to this, if there is a static method in a class that is invoked once by the static constructor, will the method (and the constructor, for that matter) remain in memory for the rest of the class's (session's) lifetime, or are these segment unloaded once they are no longer needed?