And yet another way: 
my %h;
push @{$h{$_ cmp $top}}, $_ for @unsorted;
my @sorted = (@{$h{0}}, sort(@{$h{1}}), sort(@{$h{-1}}));

[download]
It's using a single pass bucket-sort as first step. Again note the absense of a sorting block.

In reply to Re^2: Optimizing a sort function (wrap-around alpha) by Anonymous Monk
in thread Optimizing a sort function (wrap-around alpha) by SineSwiper

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