RAM is not as fast in practice as the specs claim, because there is a lot of overhead in accessing it. I did some latency benchmarking on my M2 Max MBP when I got it last year. As long as the working set fits in L1 cache, read latency is ~2 ns. Then it starts increasing slowly, reaching ~10 ns at 10 MiB. Then there is a rapid rise to ~100 ns at 100 MiB, followed by slow growth until ~10 GiB. Then the latency starts increasing rapidly again, reaching ~330 ns at 64 GiB.