I finally managed to carve out time to read Lara Hogan's Designing for Performance and I'm really glad that I did. Ms Hogan guides the reader through everything important about performance: from why it's important, through how to make the changes, and (perhaps most importantly) tips on how to bring about a culture change in your organisation. I highly recommend picking up a copy. Below are my sketchnotes (click picture for larger versions) and a few more thoughts on the excellent book.
Ms Hogan begins by focusing on explaining how Performance is the same as User Experience, and goes into some of the technical details about what factors contribute to performance. One thing that I appreciated being reminded of is that, especially on mobile, Latency trumps bandwidth as a constraining factor.
The next section of the book talks about page speed, optimising images, optimising your front-end code, and responsive web design. It offers lots of practical tips and things to think about.
Ms Hogan then goes on to talk about process-related things: when and how to measure and iterate on performance, and offers advice on making decisions that are between aesthetics and performance. There's lots of useful stuff there for both developers and designers.
The last chapter is heavy: it deals with introducing a performance culture to your organisation. A lot of the lessons and advice ring familiar from advice on bringing cultural change to accept responsive web design as the norm, and of bringing a focus on User-Centered Design. Ms Hogan again offers lots of practical advice that will be very useful in championing performance as a key measure of success, and therefore bringing more decisions back to the user experience of your site or app.
Go buy the book: you'll find bunches of stuff that you can apply to your work that will make a difference for you and your users.