I think it depends a lot on the system, c-runtime 
ActivePerl v5.8.9 built for MSWin32-x86-multi-thread, Binary build 825
+ [288577]
           Rate unpack_C unpack_a    split    regex
unpack_C 3.48/s       --      -5%      -7%      -9%
unpack_a 3.66/s       5%       --      -3%      -4%
split    3.76/s       8%       3%       --      -1%
regex    3.82/s      10%       4%       1%       --

           Rate unpack_C    regex unpack_a    split
unpack_C 3.56/s       --      -5%      -5%      -6%
regex    3.74/s       5%       --      -0%      -1%
unpack_a 3.74/s       5%       0%       --      -1%
split    3.79/s       7%       2%       1%       --


Rate    split unpack_C    regex unpack_a
split    3.45/s       --      -4%      -9%     -25%
unpack_C 3.58/s       4%       --      -6%     -22%
regex    3.79/s      10%       6%       --     -18%
unpack_a 4.60/s      34%      29%      21%       --

[download]
The newer versions (built using MinGW) are more consistent between runs 
C:\perl\5.10.1\bin\MSWin32-x86-multi-thread\perl.exe

           Rate unpack_C    regex    split unpack_a
unpack_C 3.66/s       --      -2%     -15%     -22%
regex    3.74/s       2%       --     -14%     -21%
split    4.33/s      18%      16%       --      -8%
unpack_a 4.70/s      28%      26%       9%       --


C:\perl\5.11.1\bin\MSWin32-x86-multi-thread\perl.exe


           Rate    regex unpack_C    split unpack_a
regex    2.74/s       --     -28%     -38%     -39%
unpack_C 3.82/s      39%       --     -13%     -14%
split    4.40/s      60%      15%       --      -2%
unpack_a 4.47/s      63%      17%       2%       --

[download]

In reply to Re^3: Convert string to array - performance challenge by Anonymous Monk
in thread Convert string to array - performance challenge by rtillian

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