Rust could just as well have an optional tracing GC for shared ownership instead of ARC, potentially improving performance rather than reducing it. Having a GC doesn't inherently make a language slower.
Yeah but let's be honest; GC languages (Go, Java, C#) usually are slower than systems languages. Systems languages just give you more, low level control over the computer from within your program. You can use that control to improve performance. Eg, you can control data locality, memory access patterns, the emitted assembler, and way more stuff.
Of course you're right - if you misuse arc, you can make your program slow. So don't misuse arc then. Rust gives you lots of options for structuring memory. If you choose badly, that's on you.
