Boost C++ Libraries

The benchmark with 100000000 64 bits integers, comparing with the std::stable_sort of the GCC 6.3 compiler shows the mentioned characteristics, running on a Intel i7-5820K CPU @ 3.30GH .

Data                           |std::stable_sort |   spin_sort  |
-------------------------------+-----------------+--------------+
random                         |     8.62        |     9.73     |
                               |                 |              |
sorted                         |     4.88        |     0.06     |
sorted + 0.1% end              |     4.92        |     0.41     |
sorted +   1% end              |     4.97        |     0.55     |
sorted +  10% end              |     5.73        |     1.32     |
                               |                 |              |
sorted + 0.1% middle           |     6.58        |     1.89     |
sorted +   1% middle           |     7.06        |     2.12     |
sorted +  10% middle           |     9.56        |     4.02     |
                               |                 |              |
reverse sorted                 |     0.13        |     0.14     |
reverse sorted + 0.1% end      |     5.22        |     0.52     |
reverse sorted +   1% end      |     5.29        |     0.66     |
reverse sorted +  10% end      |     6.03        |     1.45     |
                               |                 |              |
reverse sorted + 0.1% middle   |     6.52        |     1.89     |
reverse sorted +   1% middle   |     7.09        |     2.12     |
reverse sorted +  10% middle   |     9.46        |     4.02     |
                               |                 |              |
-------------------------------+-----------------+--------------+