Technically yes, but if you only use it when you need it, it's often not a performance concideration. And for systems programming, the often overlooked truth i

Technically yes, but if you only use it when you need it, it's often not a performance concideration. And for systems programming, the often overlooked truth is that people care far less about perfect performance than they do about control - ref counting doesn't give up control to a mysterious oracle running in the background which may or may not wreck your performance in hard to predict ways, it just pays a known cost at the time you use it based on how you're using it. (that's not to say performance is irrelevant, but it's not always the top concern, and with control you can always rewrite slow code as needed). The obvious question is "why can't we have an optional modern garbage collector built into a systems language?", and it's a good question (I remember reading there was one in rust for a while during early development, but it got removed), I think the main reason is that high quality garbage collectors are incredibly complicated, with many trade offs, and a gc that combines well with the rest of a language and various alternative memory tracking solutions is harder than most. The projects that really want one can always implement their own and choose their own tradeoffs, so there's not many use-cases where a generic language-provided one would justify the complexity of implementing it within the language.