Why is D's GC slower than GO's?

[Imperatorn]

On Saturday, 29 October 2022 at 10:04:01 UTC, IGotD- wrote:
> On Saturday, 29 October 2022 at 09:42:32 UTC, Walter Bright 
> wrote:
>>
>> It's literally impossible for me to stop anyone who wants to 
>> improve the GC. It's all open source, and Boost licensed. It's 
>> even designed to be pluggable.
>
> No they can't because D doesn't have a built in managed pointer 
> type and they are limited to a subset of GC algorithms (even 
> limited among the tracing GC ones).
>
> It is possible to use a library custom GC type but then 
> runtime/phobos don't use these so replacing the GC in the 
> entire program isn't possible.
>
> Many have tried to explain this numerous times but you just 
> ignore this obvious fact.

What would be some theoretical ways to improve?

For example, adding a custom gc type, are we talking months or 
work? Years? What would it look like? Sorry for being ignorant on 
this