Investigation: downsides of being generic and correct

[Dicebot]

On Thursday, 16 May 2013 at 11:37:14 UTC, bearophile wrote:
> Dicebot:
> In the first of his posts I don't see -noboundscheck used, and 
> it compares different algorithms from C++ (a switch) and D (two 
> nested ifs, that are not optimal).
>
> From my experience if you have some care you are able to write 
> D code for LDC that is about as fast as equivalent as C code, 
> or better.

Sure. I am not interested in benchmarks. What made me curious was 
"what made this code so slow if you _don't_ have some care".