Are Python docstrings and comments stored in memory when a module is loaded?

I've wondered if this is true, because I usually document my code well; may this affect memory usage?
Usually every Python object has a __doc__ method. Are those docstrings read from the file, or processed otherwise?
I've done searches here in the forums, Google and Mailing-Lists, but I haven't found any relevant information.  
Do you know better?
They are getting read from the file (when the file is compiled to pyc or when the pyc is loaded -- they must be available under object.__doc__) but no --> this will not significantly impact performance under any reasonable circumstances, or are you really writing multi-megabyte doc-strings?
Are Python docstrings and comments stored in memory when a module is loaded?