Permutation Sort Algorithm Very Slow

[Agora via Digitalmars-d-learn]

Hi.

I've found some code

import std.stdio, std.algorithm;

void permutationSort(T)(T[] items) pure nothrow {
     while (items.nextPermutation) {}
}

void main() {
     auto data = [2, 7, 4, 3, 5, 1, 0, 9, 8, 6, -1];
     data.permutationSort;
     data.writeln;

}

This code is running very slow

Runtime Seconds: 5-6

Why is running slow?

Sorry for my bad english :( :)

Thank you :)