Can this implementation of Damm algorithm be optimized?

[Nestor via Digitalmars-d-learn]

On Sunday, 12 February 2017 at 05:54:34 UTC, Era Scarecrow wrote:
> On Saturday, 11 February 2017 at 21:56:54 UTC, Era Scarecrow 
> wrote:
>>  Just ran the unittests under the dmd profiler, says the 
>> algorithm is 11% faster now. So yeah slightly more optimized.
>
> Ran some more tests.
>
> Without optimization but with with 4 levels (a 2.5Mb table), it 
> gains to a whopping 27%!
> However with optimizations turned on it dwindled to a mere 15% 
> boost
> And optimization + no bounds checking, 2 & 4 levels both give a 
> 9% boost total.
>
> Testing purely on 8byte inputs (Brute forced all combinations) 
> receives the same 9% boost with negligible difference.
>
> Safe to say going higher levels isn't going to give you 
> sufficient improvement; Also exe file is 3Mb big (but 
> compresses to 150k).

Wow!
Thanks for the interest and effort.