Does it need to be a regex? If you can live with an exact match, then I'd use a hash:
my %want_global = map { ($_ => 1) } qw(
  THIS
  THAT
  ANOTHER
);

...
if ( $want_global{$global} ) {
 ...
}

[download]
If you really need to have regexes, then put them in an array instead of a single regex, it will generally perform better than a joined single regex (and put the most likely things to match first, if possible):
my @wanted_re = (
  qr/^AB/,
  qr/^CD/,
);
sub want_global {
  my $g = shift;
  for my $re (@wanted_re) {
    return 1 if $g =~ /$re/;
  }
  return;
}

[download]
Update: I see that maybe you want 'unwanted global' logic...whatever...the above still applies...adjust to suit needs.

In reply to Re: Speed of Perl Regex Engine by runrig
in thread Speed of Perl Regex Engine by Clovis_Sangrail

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