use Benchmark 'cmpthese';
$match=0;
$string="";

cmpthese -5, {
slower => <<'EOFCODE',
for my $i (0..100) {
	$::string="${i}test";
    if($::string =~ /(?:est|\d)/){
        $::match++;
    }
}
EOFCODE

slower2 => <<'EOFCODE',
for my $i (0..100) {
	$::string="${i}test";
    if($::string =~ /(?:\d|est)/){
        $::match++;
    }
}
EOFCODE
faster => <<'EOFCODE',
for my $i (0..100) {
	$::string="${i}test";
    if ($::string =~ /est/ || $::string =~ /\d/){
        $::match++;
    }
}
EOFCODE
faster2 => <<'EOFCODE',
for my $i (0..100) {
	$::string="${i}test";
    if ($::string =~ /\d/ || $::string =~ /est/){
        $::match++;
    }
}
EOFCODE
};

__END__
Benchmark: running faster, faster2, slower, slower2, each for at least 5 CPU seconds...
    faster:  5 wallclock secs ( 5.36 usr +  0.00 sys =  5.36 CPU) @ 3157.84/s (n=16926)
   faster2:  5 wallclock secs ( 5.39 usr +  0.00 sys =  5.39 CPU) @ 2859.21/s (n=15414)
    slower:  5 wallclock secs ( 5.44 usr +  0.00 sys =  5.44 CPU) @ 2673.59/s (n=14539)
   slower2:  6 wallclock secs ( 5.36 usr +  0.00 sys =  5.36 CPU) @ 2881.69/s (n=15443)
          Rate  slower faster2 slower2  faster
slower  2674/s      --     -6%     -7%    -15%
faster2 2859/s      7%      --     -1%     -9%
slower2 2882/s      8%      1%      --     -9%
faster  3158/s     18%     10%     10%      --

##</code><code>##

use Benchmark 'cmpthese';
$match=0;
@strings=qw(
            abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz
            abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz_est
            abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz_0
            est_abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz
            0_abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz
            abcdefghijklmnopqrstuvwxyzabcdefghijk_est_lmnopqrstuvwxyz
            abcdefghijklmnopqrstuvwxyzabcdefghijk_0_lmnopqrstuvwxyz
           );


cmpthese -5, {
slower => <<'EOFCODE',
for my $str (@::strings) {
    if($::string =~ /(?:est|\d)/){
        $::match++;
    }
}
EOFCODE

slower2 => <<'EOFCODE',
for my $str (@::strings) {
	if($::string =~ /(?:\d|est)/){
        $::match++;
    }
}
EOFCODE
faster => <<'EOFCODE',
for my $str (@::strings) {
	if ($::string =~ /est/ || $::string =~ /\d/){
        $::match++;
    }
}
EOFCODE
faster2 => <<'EOFCODE',
for my $str (@::strings) {
	if ($::string =~ /\d/ || $::string =~ /est/){
        $::match++;
    }
}
EOFCODE
};

__END__

##</code><code>##

Benchmark: running faster, faster2, slower, slower2, each for at least 5 CPU seconds...
    faster:  4 wallclock secs ( 5.25 usr +  0.00 sys =  5.25 CPU) @ 103837.90/s (n=545149)
   faster2:  6 wallclock secs ( 5.24 usr +  0.00 sys =  5.24 CPU) @ 103939.83/s (n=544125)
    slower:  5 wallclock secs ( 5.25 usr +  0.00 sys =  5.25 CPU) @ 133356.57/s (n=700122)
   slower2:  5 wallclock secs ( 5.28 usr +  0.00 sys =  5.28 CPU) @ 132805.94/s (n=701481)
            Rate  faster faster2 slower2  slower
faster  103838/s      --     -0%    -22%    -22%
faster2 103940/s      0%      --    -22%    -22%
slower2 132806/s     28%     28%      --     -0%
slower  133357/s     28%     28%      0%      --