AFAIK Perl treats __END__ like an EOF, i.e. it will stop reading the file at that point, so the amount of data after an __END__ shouldn't make a difference. Everything before that does have to be read before it is parsed and executed, of course. If you have large amounts of data, it's probably better to put that in an external file, though. It is fairly common to put large POD documents after an __END__, though.