I did a 
time perl -pe '$r = substr(rand(), 2); $_ = "$r\t$_"' input | sort -n 
+| cut -f 2- > dev/null

[download]
on the same files, and my results are: 
nr of lines          real       user        sys
        100       0m 0.010s  0m 0.010s   0m 0.000s
       1000       0m 0.051s  0m 0.010s   0m 0.030s
      10000       0m 0.264s  0m 0.180s   0m 0.040s
     100000       0m 2.608s  0m 1.640s   0m 0.140s
    1000000       0m40.640s  0m17.550s   0m 1.060s
   10000000      17m14.639s  3m30.830s   0m27.200s

In reply to Re^5: Strategy for randomizing large files via sysseek by Anonymous Monk
in thread Strategy for randomizing large files via sysseek by Anonymous Monk

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