s/\G(.{1,80})/$1\n/gs;
print;

##</code><code>##

use Benchmark qw(cmpthese);
open(STDERR,">/dev/null");
cmpthese (10000,
            {
              match => sub { local $_ = "abcde    " x 100;
                             print STDERR "$1\n" while /\G(.{1,80})/gs;
                           },
              swap  => sub { local $_ = "abcde    " x 100;
                             s/\G(.{1,80})/$1\n/gs;
                             print STDERR $_;
                           },
            });

##</code><code>##

Benchmark: timing 10000 iterations of match, swap...
     match:  1 wallclock secs ( 1.26 usr +  0.01 sys =  1.27 CPU) @ 7874.02/s (n=10000)
      swap:  1 wallclock secs ( 1.01 usr +  0.01 sys =  1.02 CPU) @ 9803.92/s (n=10000)
        Rate match  swap
match 7874/s    --  -20%
swap  9804/s   25%    --