use Benchmark qw( cmpthese );

cmpthese( 10_000_000, { lower => sub { 'network' =~ /^network$/ },
                        upper => sub { 'networK' =~ /^networK$/ } } );
__END__
           Rate lower upper
lower 3174603/s    --   -9%
upper 3496503/s   10%    --