Strange CTFE issue, string replacement

[Jethro via Digitalmars-d-learn]

On Sunday, 9 April 2017 at 19:55:57 UTC, Stefan Koch wrote:
> On Sunday, 9 April 2017 at 19:38:33 UTC, Jethro wrote:
>> [...]
>
> The constructor is nuts.
> You do not need to zero the string!
>
> Also avoid templates if you can.

Please don't criticize banal stuff by choosing one meaningless 
line and calling the whole thing "nuts". It's a waste of time. I 
zero'ed it because it helps in debugging and for other errors.(if 
used in C terminated like string usage it helps to have the 
string actually terminate at some point)


My questions still stand though. Why is it 10x the speed and 
memory?!?!