Re: Premature and micro optimization...

How very odd!

My testing on Win2k, ActivePerl 5.8.8 shows that the case of the data doesn't affect the timing, and that old_way is consistently just shy of 50% faster than with_tr.

Upper case data
===============
            Rate with_tr old_way
with_tr 183850/s      --    -32%
old_way 272269/s     48%      --

Lower case data
===============
            Rate with_tr old_way
with_tr 182262/s      --    -33%
old_way 270854/s     49%      --
[download]

Benchmark code:

#!/usr/bin/perl

use strict;
use warnings;

use Benchmark qw( cmpthese );

my $TIMES = shift(@ARGV) || -3;

my $upper_id_string = "ABCD1EFGHI2J.a01f2345b067cde890f12gab345678c9";
my $lower_id_string = "abcd1efghi2j.a01f2345b067cde890f12gab345678c9";

sub old_way {
   my $string = shift;
   return split( /\./, $string, 2 );
}

sub with_tr {
   my $string = shift;
   my( $id, $session ) = split( /\./, $string, 2 );
   $id =~ tr/a-z/A-Z/;
   return ( $id, $session );
}

{
   print("Upper case data\n");
   print("===============\n");

   our $string = $upper_id_string;

   cmpthese($TIMES, {
      old_way => 'use strict; use warnings; our $string; my @rv = old_
+way($string); 1',
      with_tr => 'use strict; use warnings; our $string; my @rv = with
+_tr($string); 1',
   }),
}

print("\n");

{
   print("Lower case data\n");
   print("===============\n");

   our $string = $lower_id_string;

   cmpthese($TIMES, {
      old_way => 'use strict; use warnings; our $string; my @rv = old_
+way($string); 1',
      with_tr => 'use strict; use warnings; our $string; my @rv = with
+_tr($string); 1',
   });
}
[download]

Of course, inlining the code saves a lot of time:

              Rate   with_tr   old_way with_tr_i old_way_i
with_tr   180473/s        --      -32%      -39%      -52%
old_way   265506/s       47%        --      -10%      -29%
with_tr_i 296058/s       64%       12%        --      -20%
old_way_i 372377/s      106%       40%       26%        --
[download]

Benchmark code:

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