Small part of a program : d and c versions performances diff.

[Larry via Digitalmars-d-learn]

The actual code is not that much slower according to the numerous 
other operations we do. And certainly faster than D version doing 
almost nothing.

Well it is about massive bitshifts and array accesses and 
calculations.
With all the optimizations we are on par with fortran numerical 
code (thanks -std=c11).

There may be an optimization hidden somewhere or just gdc having 
to mature.

Dunno. But don't get me wrong, D is a fantastic language.