High Performance Websites and Even Faster Websites
These two on website performance are good, though they're a bit dated (pre http2 etc).
High Performance Browser Networking
I never fully read this one but it's really good, probably required reading if you're serious about webdev
CSS: BEM/OOCSS/SMACSS methodologies, they make you think critically about the structure of you styles. Harry Roberts does good writeups on maintainable css.
What are they about? Essentially, optimizing your HTTP responses for the ways in which actual web browsers make HTTP requests. Any web performance analysis tool worth using (like YSlow and PageSpeed – both of which Steve Souders was involved in btw) recommended the practices outlined in those books.
So, no. I don't think a new book with updated practices says anything about the protocol. The optimization tips from this book will simply become widespread common knowledge the same way they did in the past.
High Performance Web Sites
Essential Knowledge for Front-End Engineers
(By Steve Souders)
And for an intro to scalability:
Building Scalable Web Sites: Building, Scaling, and Optimizing the Next Generation of Web Applications
(By Cal Henderson)