> Do you have examples where Swift suffers compared to other languages solely because of ARC? Literally all of them. Every single program where the ARC system

> Do you have examples where Swift suffers compared to other languages solely because of ARC? Literally all of them. Every single program where the ARC system is actually widely used. Swift otherwise generates really good code, and should be meeting/beating Java most of the time, but if the ARC system is used, performance instantly takes a massive hit. This is very visible in the small synthetic benchmarks at: https://benchmarksgame-team.pages.debian.net/benchmarksgame/fastest/swift.html https://benchmarksgame-team.pages.debian.net/benchmarksgame/... In every benchmark where it was possible to write the program so that no references are updated in the hot loop, Swift comes out really impressive, beating Java. In benchmarks where reference updates are unavoidable, performance is more in line with Python. > Also, is this something that Apple might theoretically make up for by optimizing their custom CPUs for it, without changing Swift? There are various theoretical ideas that have been bounced about for decades, but so far none of those has panned out. While Apple might do that too, at this point they seem to be chasing the opposite approach: https://github.com/apple/swift/blob/master/docs/OwnershipManifesto.md https://github.com/apple/swift/blob/master/docs/OwnershipMan... Essentially, nicking the ownership/lifetimes system out of Rust, to avoid updating references wherever possible. The main difference from Rust will be that the current way of doing things will still be possible and the default, but programmers can opt into more performance by decorating their types with lifetimes. I am cautiously optimistic for this approach: I love Rust, but learning it did definitely feel like being tossed right into the deep end. Which was filled with sharks. If Swift can succeed in a softer approach of introducing lifetimes, that might help the wider introduction of the concept.