GC generally optimises for throughput over latency. But there is also another cost: high-throughput GC usually uses more memory (sometimes 2-3x as much!). Arc keeps your memory usage low and can keep your latency more consistent, but it will often sacrifice throughput compared to a GC tuned for it. (Of course, stack allocation, where possible, beats them all, which is why rust and C++ tend to win out over java in throughput even if the GC has an advantage over reference counting, because java has to GC a lot more than other languages due to no explicit stack allocation)