$self->{'Big_List'} = [many elements];

##</code><code>##

sub GetBigList {
    my $self = shift;
    return $self->{'BigList'};
}

sub SomeOperation {
    my $self = shift;

    foreach my $element ( @{$self->GetBigList()} ) {
        # do stuff to element, etc.
    }
}

##</code><code>##

sub SomeOperation {
    my $self = shift;

    foreach my $element ( @{ $self->{'Big_List'} } ) {
        # do stuff to element, etc.
    }
}