I am not going to say very much about this book. I think the more important feature is 'troubleshooting'. In the context of a small volume such as this one you are not going to find an exhaustive guide to detecting the causes of all problems. However this book does make a useful starting point and is just about what the computer literate user who is neither a hardware nor software engineer needs. Things that you cannot detect and correct with the help of this book probably need the attention of a specialist.
On the optimising side, this is a book that you can browse. When you see something that you think might be useful to you (such as using multiple languages - one of my clients was delighted to find how easy it was to switch his keyboard between various European languages) then stop and follow the author's simple step by step guide.