For decades, computing performance was easy to reduce to a few headline specifications. CPUs were sold on clock speed and core count, GPUs on shader throughput and later teraFLOPS , memory on frequency, and storage on sequential transfer rates. Those numbers still have value, but modern processors have become so extraordinarily capable of performing arithmetic that another problem increasingly dictates how much of that theoretical performance can actually be used: getting data where it needs to go, when it needs to be there .

A modern CPU core can execute multiple instructions