See discussion of "capacity factor" here:
https://news.ycombinator.com/item?id=41858892
It's the same as when we talk about the efficiency of a GEMM kernel on a particular piece of hardware. As efficiency approaches 100% the kernel is saturating the hardware's capacity to perform multiply/add.
The term "capacity factor" should generally always be used for that concept, because "efficiency" has its own, different, meaning for power plants.