this post was submitted on 26 Feb 2024
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Programming
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To be fair, Swift uses reference counting instead of garbage collection which has different tradeoffs than GC but does incur a performance penalty.
I wish more languages used ref counting. Yes, you have to be careful of circular refs, but the tradeoff is simplicity, speed, lack of needing threads in the runtime, and predictability. Rust gives you special data structures for ref counting for a reason.
Ref counting is just a very basic GC. I'd be surprised if a ref counted language performed better than a GC one. Sure, the program won't temporarily halt in order to run the GC, but every copy/destroy operation will be slower.
When Apple introduced the iPhone they required automatic reference counting to be used in Objective-C rather than tracing garbage collection (the language supported both) due to performance reasons (iPhones were significantly slower than Macs). At least Apple seems to think that reference counting is faster than tracing garbage collectors. The compiler can do a lot to remove unnecessary releases and retains. Additionally each retain is just incrementing an integer, and each release is just decrementing an integer and comparing the integer to 0, so the overhead is pretty small.
If the compiler optimizes away some RC then I see how it can be faster.