my $exports = \@{"$pkg\::EXPORT"};
  # ...
  my $export_cache = ($Cache{$pkg} ||= {});
  my $args = @_ or @_ = @$exports;

  if ($args and not %$export_cache) {
    s/^&//, $export_cache->{$_} = 1
      foreach (@$exports, @{"$pkg\::EXPORT_OK"});
  }