The performance begins with the CPU

As we have observed in the earlier chapters, an efficient program is one that makes full use of the available hardware resources and does not waste them for tasks that are not needed. A high-performing program cannot be described so simply because performance can be defined only with respect to specific targets. Nonetheless, in this book, and in particular, in this chapter, we are largely concerned with the computational performance or throughput: how fast can we solve a given problem with the hardware resources we have? This type of performance is closely related to efficiency: our program will deliver the result faster if every computation it executes brings us closer to the result, and, at every moment, we do as much computing as possible.

This brings us to the next question: just how much computing can be done, say, in one second? The answer, of course, will depend on what hardware you have, how much of it, and how efficiently your program...