My loan of this from the library was almost finished before I’d had time to finish it – I had the choice of reading it in one day or not reading it at all. Thankfully I chose to read it in a couple of sittings, and I’m really glad I did.
Chapter one offers advice for getting the page to render quickly, predominantly by moving the script elements to the end of the page near the closing of the body element. Other techniques are also covered: deferred scripts in IE, and delayed loading of script using XHR or other methods and then loading the new code using a <script> element which is added to the DOM.
Chapters 4 and 5 look at slow language constructs including loop performance, if-then versus switch and lookup tables. There’s a discussion of stack overflow and the stack sizes in the various browsers, and some techniques to avoid it happening. Writing efficient regular expressions is covered in some detail.
Chapter 7 looks at Ajax and the different in performance when using the data formats XML, JSON, JSON-P, HTML compared to custom data transmission formats. Response caching using HTTP headers is also covered.
Chapter 8 covers practices to get good performance including lazy loading and using native methods for good performance.
The book is fairly short but covers the material with a good amount of detail, making it both a quick and an informative read.