I just looked again, and your shufl sorts things in-place. That's not fair. But it doesn't seem to make a lot of difference in the benchmark time. I also tried changing qshuf to not be inconsistent, like so: 
sub qshuf {
     my %hash;
     sort { $hash{$a}{$b}||=(.5 <=> rand 1) } @_;
}

[download]
That is, it caches the value for each pairwise comparison, but it still doesn't shuffle well. Of course, there is the possibility of a > b > c > a...

Update: I have a winner! 

sub qshuf {
     my %hash;
     sort { ($hash{$a}||=rand 1) <=> ($hash{$b}||=rand 1) } @_;
}

         Rate  xform  slice  shufl  qshuf
xform  65.6/s     --   -34%   -72%  -100%
slice  99.7/s    52%     --   -57%  -100%
shufl   233/s   255%   133%     --   -99%
qshuf 44494/s 67764% 44534% 19019%     --

permutation |  slice |  xform |  shufl |  qshuf
--------------------------------------------------
Std. Dev.   | 69.974 | 58.895 | 53.532 | 62.689

[download]
Caution: Contents may have been coded under pressure.

In reply to Re^4: Is this a fair shuffle? by Roy Johnson
in thread Is this a fair shuffle? by Roy Johnson

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