This separate patch to simplify the print_kth() function
by removing the comparison from it, is simple and
has a significant perf advantage. Tests pass so I'll apply.

I'll adjust the commit log to summarise the perf change,
but I notice the change isn't as great as yours on my sandybridge i3 system.
Benchmark results for both the rebased memory rework and
the simple print_kth() optimization attached.

thanks!
Pádraig.