200-600x slower Dlang performance with nested foreach loop

[FeepingCreature]

On Wednesday, 27 January 2021 at 02:14:39 UTC, H. S. Teoh wrote:
> Yes, definitely try this.  This will completely eliminate the 
> overhead of using an AA, which has to allocate memory (at 
> least) once per entry added.  Especially since the data has to 
> be sorted eventually anyway, you might as well sort first then 
> use the sortedness as a convenient property for fast 
> de-duplication.  Since .uniq traverses the range linearly, this 
> will be cache-friendly, and along with eliminating GC load 
> should give you a speed boost.
>
>
> T

Associative arrays allocate per entry added?!

https://github.com/dlang/druntime/blob/master/src/rt/aaA.d#L205 
Oh God, associative arrays allocate per entry added!