About twenty years ago I can remember working very hard to get a piece of code down to 256 bytes. That was critical because it affected the addressing mode that I could use. These days we can have similar constraints with cache sizes and page sizes. Page faults can be expensive and loops that exceed the cache size can seriously degrade performance. The problem is that such considerations are very hardware dependant and so most of us should not be worrying about them.
Speed is another element that needs de-emphasis in the minds of many programmers.
Too much speed can sometimes be a problem. The programmers responsible for such products need to provide some mechanism so that the user can control the scroll speed. On the other hand those working on such things as film animation need every fraction of increased speed they can get. Those writing code for small, embedded systems might benefit from some aspects of this book but for many others the problem is what is not there. Both performance and code size can be counter-intuitive.