I’m not denying that Apple has better ARC performance. It’s that I don’t understand how an application would use less memory on ARM than x86. I’d expect the ARM code to run faster (as a result of being able to do atomic operations faster), but I don’t see how that translates to less memory usage
In one of those random “benchmark tests” online where someone opened several applications on an M1 Mac with 8GB RAM and did some work on those, they kept Activity Monitor open alongside and pointed to the increase in swap at some stage. So it seems like the swap is fast enough and is used more aggressively. That reduces the amount of RAM used at any point in time. The data in RAM has also benefited from compression in macOS for several years now.
Read up on the performance overhead of GC across other languages. They’re messy and can lock up periodically. They take up significant ram and resources.