XML::Twig->new( twig_roots => { content => \&content }, twig_print_outside_roots => 1, keep_spaces => 1, ) ->parsefile( 'ginormous.xml');

exit;

sub text { 
my( $t, $content) = @_;
my $snipped = substr($content->text, 0, 1000000);
$content->set_cdata($snipped);

$t->flush; }