It's tunable, --cache-gb N on the CLI. In my sweep the speed barely moved between a 1GB and 6GB cache (43% vs 70% hit rate, same tok/s) because right now the bottleneck is GPU dispatch, not the SSD. so more RAM doesnt buy much yet. once the kernel work lands it should start to matter, so on 32GB I would just set 8 and let it age well. Also the hit rates themselves answer the "can you even know which experts stay hot" question, reuse across tokens is very real.