Finding large difference b/w execution time of c++ and D codes for same problem

[Joseph Rushton Wakeling]

On 02/13/2013 02:26 PM, Marco Leise wrote:
> You get both, 50% more speed and more precision! It is a
> win-win situation. Also take a look at Phobos' std.math that
> returns real everywhere.

I have to say, it's not been my experience that using real improves speed. 
Exactly what optimizations are you using when compiling?