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

[IGotD-]

On Sunday, 30 October 2022 at 07:52:09 UTC, Ola Fosheim Grøstad 
wrote:
>
> (Swift and Go are usually not considered system level.)

Swift is an interesting example of a possible system level 
language, but you have to trip lightly in order not to get heap 
allocations under the hood. Structs (which are value types) can 
end up on the heap when you use protocols together with structs. 
If you start to copy these heap allocated structs, you will 
quickly start to do heap allocations under the hood.

This video gives a little explanation about.
https://developer.apple.com/videos/play/wwdc2016/416/

If pay attention you should be able to avoid these.

With multithreaded system services, Swift seems to be a very good 
alternative. Atomic reference counting is here very suitable. 
Also lately there have been a lot of work on the concurrent model 
for Swift and it supports async/await, concurrent actors.

For the most low level programming Swift isn't an alternative but 
for system services inside an existing OS there should Swift do 
fine. Also, Swift seems to be a good fit for game programming as 
well.