200-600x slower Dlang performance with nested foreach loop

[mw]

On Tuesday, 26 January 2021 at 17:40:36 UTC, methonash wrote:
> foreach( i, ref pStr; sortedArr )
> {
>     foreach( j, ref cStr; sortedArr[ i + 1 .. $ ] )
>     {
>         if( indexOf( pStr, cStr ) > -1 )
>         {
>             // ...
>         }
>     }
> }
>
> Before adding the code excerpt above, the Dlang program was 
> taking ~1 second on an input file containing approx. 64,000 
> strings.

What's the typical length of your strings?