Ch. 3 – DOM Scripting – This was written by Stoyan Stefanov (http://phpied.com). It covers the interactions between the browsers’ scripting engines and DOM engines. It has very good explanations of html collections and how to work with them in the most performant way. It covers browser repaints and reflows and how to minimize them. And it goes over event delegation and using parent event handlers to handle events on children to minimize the quantity of event handlers on a page.
Ch. 4 – Algorithms and Flow Control – This chapter discusses the performance implications of how you use loops and conditionals, and how you structure your algorithms. It includes comparisons of the different loop constructs, of recursion vs. iteration, etc.
Ch. 5 – Strings and Regular Expressions – This was written by Steven Levithan (http://blog.stevenlevithan.com/). This chapter explains the common pitfalls to nonperforming string operations and regexes and how to avoid them. In doing so, the author describes what the browser is doing under the covers… interesting, but probably needs to be used as a reference. (i.e. not something I’ll just remember after one read.)
Ch. 7 – Ajax – This was written by Ross Harmes (http://techfoolery.com/). – “This chapter examines the fastest techniques for sending data to and receiving it from the server, as well as the most efficient formats for encoding data.” There are some interesting things in this chapter that I rarely see talked about elsewhere, such as Multipart XHR, image beacons, and JSON-P.
Ch. 8 – Programming Practices – Covers some programming practices to avoid, such as avoiding double evaluation, and not repeating browser detection code unnecessarily. Also covers practices to use, such as object and array literals and using native methods when available.