A benchmark, mostly GC

[bearophile]

dsimcha:

> My optimizations make very little difference on this benchmark, but for 
> good reason:  It's not a very good GC benchmark.  I ran it with my GC 
> profiling code enabled and it only spends around 10% of its execution 
> time in GC.  We need to figure out why else this benchmark may be so slow.

Thank you for your timings. At the moment I don't know why this D program is slow.

Bye,
bearophile