On the SAA exam, high-performance architecture (Domain 3) is 24%. If security was an "allow/block" verdict and resilience a "blast radius" problem, the high-performance domain is a placement-and-parallelism problem: "to reduce latency and increase throughput, where do you put data and compute, and how do you parallelize?" The reason test-takers who memorize fragments like "DAX is μs, FSx Lustre is ML" get stuck is that what the exam asks is not a service name but "where is this workload's bottleneck, and do you solve it with caching, proximity, parallelism, or dedicated hardware?"
Every choice in the high-performance domain reduces to two big levers