use Benchmark;
my $n = 1000;
open(STDERR,">/dev/null");
cmpthese (1000,
            {
              match => sub { local $_ = "abcde    " x $n;
                             print STDERR "$1\n" while /\G(.{1,80})/gs;
                           },
              swap  => sub { local $_ = "abcde    " x $n;
                             s/\G(.{1,80})/$1\n/gs;
                             print STDERR $_;
                           },
              subst => sub { local $a = "abcde    " x $n;
                             $b='';
                             $b .= substr( $a, 0, 80, '')."\n" while length($a) >80;
                             print STDERR "$b$a";
                           },
            });

##</code><code>##

Benchmark: timing 1000 iterations of match, subst, swap...
     match:  1 wallclock secs ( 0.97 usr +  0.00 sys =  0.97 CPU) @ 1030.93/s (n=1000)
     subst:  1 wallclock secs ( 0.58 usr +  0.00 sys =  0.58 CPU) @ 1724.14/s (n=1000)
      swap:  1 wallclock secs ( 0.75 usr +  0.00 sys =  0.75 CPU) @ 1333.33/s (n=1000)
        Rate match  swap subst
match 1031/s    --  -23%  -40%
swap  1333/s   29%    --  -23%
subst 1724/s   67%   29%    --