A benchmark can be repeatable and still support the wrong decision. I reached that point after 21 one-hour Valkey 9.0 runs across seven Amazon ElastiCache node designs. The same fixed workload pushed the general-purpose M family to 99.89% to 100% memory, while the memory-optimized R family finished with roughly 27% to 34% headroom. A flat Intel-versus-Graviton ranking would have converted different operating regimes into a confident but false architecture conclusion.

I stopped treating the matrix as a CPU race and reframed the program around two complementary views: fixed workload for the application-placement decision, and fixed pressure for the systems comparison. The result is a decision framework that keeps capacity, reliability, and investment risk visible before a team commits to an ElastiCache design.