Well, since I don't have a working intermediate-level knowledge of .Net, you could assume that I wont buy it
You might find it useful to spend a chapter on what algorithmic complexity is. I find that most people, while they do have a perfectly good understanding of what it is and why it's important, have no idea how to describe it, and don't understand the lingo that is most commonly used. It would be a shame to write a whole book on performance, only to have it fly over the heads of its readers.
The common denominator in the popular books around here is that the examples are simple and intuitive. It would seem that software developers tend to have a certain learning style whereby the examples are more valuable than body of text describing it; if they're overwhelmed by the example, they may not even read the description.
For the record, I believe that it's critical to never sacrifice code readability for speed, so I won't be advocating those kinds of tasks.
Never? You sure you don't want to add some qualifiers to that statement? There are absolutely cases where speed is more important than readability, but the occurrence is so low that it's reasonable to not address them.