Why is this D code slower than C++?

[Bill Baxter]

Dave wrote:
> Bradley Smith wrote:
>> Thanks for all the suggestions. It helps, but not enough to make the D 
>> code faster than the C++. It is now 2.6 times slower. The render times 
>> are now approx. 13 sec for raytracer_d and approx. 5 sec for 
>> raytracer_cpp.
>>
>> Here are the changes I've made. Attached is the new code.
>>
>>   Call RegisterClass outside of assert. (Broken if -release used)
>>   Apply -release option. (Increases speed in an unknown way)
>>   Converted templates to regular functions. (Templates not being inlined)
> 
> Are you sure? I know templates can be/are inlined and I guess I haven't 
> noticed anywhere they aren't were I'd expect a regularly defined 
> function to be inlined.

I changed a bunch parameters to inout after discovering that it made a 
difference for the Intersect method.  It could be that I had the 
template parameters as inout at the time when getting rid of the 
templates seemed to make a difference.

That's evil that inout disables inlining.
Seems like inout params would be easier to inline than regular 
parameters, but I guess not.

--bb