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Adding your optimization to BrowerUK's version, we get the best yet.
sub ikegami (@) { my @a=@_; my $i=@a; my $n; my $x; map +( $n=rand($i--), $x=$a[$n], $a[$n]=$a[$i] )[1], @a }
Rate naive listutil runrig broweruk ikegami naive 636/s -- -6% -19% -26% -37% listutil 675/s 6% -- -14% -21% -33% runrig 785/s 23% 16% -- -9% -22% broweruk 859/s 35% 27% 9% -- -15% ikegami 1010/s 59% 50% 29% 18% --

Of course, this doesn't always help. For example, try shuffling somewhat long strings.

our @data = map { 'x' x 1000 } 1..1000; cmpthese -3, { map { $_ => "$_ \@data" } qw/naive listutil broweruk ru +nrig ikegami/ };
Rate runrig naive ikegami listutil broweruk runrig 118/s -- -10% -40% -43% -86% naive 131/s 11% -- -34% -37% -85% ikegami 197/s 68% 51% -- -5% -77% listutil 207/s 76% 58% 5% -- -76% broweruk 860/s 632% 558% 336% 315% --

Update: runrig pointed out that my shuffle was broken. I changed $a[$n] to $x=$a[$n] to fix it. It slowed down my solution, but not by much.

In reply to Re^2: About List::Util's pure Perl shuffle() by ikegami
in thread About List::Util's pure Perl shuffle() by blazar

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