mea culpa, fellow monk, but I must disagree with your answer. Yes, the benchmarks say something but it is what they say I feel needs deeper interpretation.

As Russ said, split is incredibly well optimized. Most of the perl internals are. There have been many C coders of wonderous talent pouring over the code to make it so. You code demonstrates that the AM was not using the correct tool, which is an answer to an unasked question.

Your four pieces of code are doing radically different things. The regex is stopping after the first match, while the split must work the entire string. Until you compare apples to apples, no conclusion can be drawn. Let us run this test and do it correctly. Note the slight changes I made to the regex code. That should result in a better comparison.

#!/usr/local/bin/perl -w
use strict;
use Benchmark;

my $testlarge = "a " x 100000;
my $testsmall = "a b c d e f";
timethese(-10,{
      One   => sub { my ($y) = (split(/\s+/,$testlarge))[0]; },
      Two   => sub { my ($y) = (split(/\s+/,$testsmall))[0]; },
      Three => sub { my $y = ( $testsmall =~ (/([^\s]*)\s+/g))[0]; },
      Four  => sub { my $y = ( $testlarge =~ (/([^\s]*)\s+/g))[0]; },
            });
mik@mach5:/home/mik/monk)./benchthis.pl
Benchmark: running Four, One, Three, Two, each for at least 10 CPU sec
+onds...
      Four: 19 wallclock secs (18.38 usr +  0.02 sys = 18.40 CPU) @  1
+.14/s (n=21)
       One: 13 wallclock secs (12.72 usr +  0.00 sys = 12.72 CPU) @  2
+.12/s (n=27)
     Three: 12 wallclock secs (10.28 usr +  0.00 sys = 10.28 CPU) @ 12
+748.55/s (n=131071)
       Two: 11 wallclock secs (10.00 usr +  0.00 sys = 10.00 CPU) @ 18
+600.60/s (n=186006)
[download]

When comparing apples to apples, it seems split is highly optimized. This more an issue of choosing the right tool for the job at hand.

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