Even stranger, cos I'm using AS1004 also. The only difference is that I'm using the 64-bit version: 

c:\test>perl -V
Summary of my perl5 (revision 5 version 10 subversion 0) configuration
+:
  Platform:
    osname=MSWin32, osvers=5.2, archname=MSWin32-x64-multi-thread
...
Characteristics of this binary (from libperl):
  Compile-time options: MULTIPLICITY PERL_DONT_CREATE_GVSV
                        PERL_IMPLICIT_CONTEXT PERL_IMPLICIT_SYS
                        PERL_MALLOC_WRAP PL_OP_SLAB_ALLOC USE_64_BIT_I
+NT
                        USE_ITHREADS USE_LARGE_FILES USE_PERLIO
                        USE_SITECUSTOMIZE
  Locally applied patches:
        ActivePerl Build 1004 [287188]
        33741 avoids segfaults invoking S_raise_signal() (on Linux)
        33763 Win32 process ids can have more than 16 bits
        32809 Load 'loadable object' with non-default file extension
        32728 64-bit fix for Time::Local
  Built under MSWin32
  Compiled at Sep  3 2008 12:22:07
  @INC:
    C:/Perl64/site/lib
    C:/Perl64/lib
    .

[download]

And I don't see the problem with 5.8.9/32-bit either: 

c:\test>\perl32\bin\perl5.8.9.exe junk.pl
Records: 400000 in 6.732 seconds
Records: 300000 in 4.329 seconds
Records: 400000 in 4.537 seconds
Records: 300000 in 3.365 seconds
Records: 400000 in 4.495 seconds

[download]

I think you should look closer at what is going on there. (I'll try to grab a copy of AS1004 32-bit and run it for comparison purposes.)

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

In reply to Re^3: Performance oddity when splitting a huge file into an AoA by BrowserUk
in thread Performance oddity when splitting a huge file into an AoA by Xenofur

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