Thanks for a nice intro in front-end performance Harry. I've found the section on prefetching especially interesting. Speed (performance) should be seen as a major _feature_ in any site/app.
But there's a lot of "It depends" regarding performance, no?
Us 'techies' must be ware of focussing too much on (premature?) micro-optimizations while forgetting some of the most obvious quick-wins: obviously limiting DNS lookups are of little worth when we are loading in unnecessary massive JS libraries or using huge images (imageoptim.com all the things!).
You touch briefly on the subject but I feel these 'simple' things are worth mentioning (more) I think.