use Benchmark 'cmpthese';
my $str = "this is the best end";
cmpthese(-5, {
  extra => sub { $str =~ /(?:[^e]+|e(?!nd))*end/ },
  plain => sub { $str =~ /.*?end/ },
  uroll => sub { $str =~ /[^e]*(?:e(?!nd)[^e]*)*end/ },
});
__END__
     extra:  11711.62/s (n=61486)
     plain:  49329.33/s (n=250593)
     uroll:  17985.61/s (n=94964)

         Rate extra uroll plain
extra 11712/s    --  -35%  -76%
uroll 17986/s   54%    --  -64%
plain 49329/s  321%  174%    --