use Data::Dumper;
sub DEVEL() { 1 };
# get sample data
my hashref = DEVEL ? require 'sampledata.pl' : do_something_costly();

# later on
if ( DEVEL ) {
    open my $fh, 'sampledata.pl' or die "sampledata.pl: $!";
    print Dumper($hashref);
}