c:\@Work\Perl\monks>perl -wMstrict -le
"use 5.010;
 ;;
 print qq{perl version $]};
 ;;
 my $s = join q{,}, 1 .. 1_500_000;
 ;;
 my $end_point = qr{ , (\d++)
   \b (??{ ++$^R != $2 || length($1) != length($2) })
   }xms;
 ;;
 my $start = time;
 use re 'eval';
 $s =~ s{
   \b (\d++) (?{ $1 }) \K
   (?: $end_point{1,32766})+
   }{-$2}xmsg;
 print qq{'$s'};
 printf qq{in %d seconds \n}, time - $start;
"
perl version 5.010001
'1-9,10-99,100-999,1000-9999,10000-99999,100000-999999,1000000-1500000'
in 18 seconds