D on quora ...

[user1234]

On Saturday, 7 October 2017 at 15:12:08 UTC, Random D user wrote:
> Actually, Manual Memory Management is slow and D's GC is slower.

Allocators should not work without an internal state. The fact 
that the heap chunk you get is mallocated or gcallocated 
shouldn't be a concern. The data structure can still use internal 
policies about how to request memory.

At the same time with allocators it's another problem. I'd say 
that the old-fashioned strategies shouldn't slow down the 
growing, even if the memory provider is better.
I don't know if you understand what i mean but in short:

     Appender!(SpecializedAllocator, int[])

shouldn't be slowest than

     Appender!(int[])

despite of the internal tweak that already exist. With allocators 
the situation is a bit confuse: who does provide the improvement ?