use strict;
use warnings;
use Benchmark qw/ cmpthese /;

my $R = 'R' x 42_000;
my $Q = 'Q' x 42_000;

sub foo {
    my $c = shift;

    pos $$c = 0;
    while ( 1 ) {
        next if $$c =~ /\G\d+R/;
        last unless $$c =~ /\w/g;
    }
}

sub foo_twostep {
    my $c = shift;

    pos $$c = 0;
    while ( 1 ) {
        next if ($$c =~ /\G[0-9]+/ and $$c =~ /\GR/);
        last unless $$c =~ /\w/g;
    }
}

cmpthese -3, { 
    R => sub { foo( \$R )},
    Q => sub { foo( \$Q )},
    R_twostep => sub { foo_twostep( \$R )},
    Q_twostep => sub { foo_twostep( \$Q )},
}
__END__
            Rate         Q R_twostep Q_twostep         R
Q         2.01/s        --      -97%      -97%      -97%
R_twostep 65.3/s     3147%        --        0%      -15%
Q_twostep 65.3/s     3147%        0%        --      -15%
R         77.1/s     3732%       18%       18%        --