How to tune numerical D? (matrix multiplication is faster in g++ vs gdc)

[Rob T]

I suggest that you move this line

GC.disable;

to the first line.

I don't see how you are doing your timings so that part is a wild 
card.

Also note that when the GC is re-enabled it can add a significant 
amount of time to the tests. You are not explicitly re-enabling 
the GC, but I don't know if the GC kicks back as part of program 
termination, it probably shouldn't but we lack precise 
documentation and cannot be certain.

I would test timings immediately after the GC is disabled and 
prior to program termination to see what affects the GC may or 
may not have on the timings.

--rt