use strict;
use warnings;
use 5.014;                  # s///r
use Benchmark 'cmpthese';

my @a = map { 
    ( 'a' x 123 ) . 
    ( ' ' x rand 2 ) .
    ( "\n" x rand 2 )
} 0 .. 999;

cmpthese -1, {
    usual  => sub { my @ret = map { s/\s*$//r } @a; \@ret },
    better => sub { my @ret = map { s/.*\S\K\s*$//sr } @a; \@ret },
    unpack => sub { my @ret = map { unpack 'A*', $_ } @a; \@ret },
};

__END__

         Rate  usual better unpack
usual   159/s     --   -88%   -95%
better 1284/s   707%     --   -56%
unpack 2899/s  1722%   126%     --