Hacker News Comments on
Website Performance Optimization
Hacker News Stories and CommentsAll the comments and stories posted to Hacker News that reference this url.
I'd be interested in other resources for this too. The best I can think of is Udacity's Web Performance Optimization class. It's by Ilya Grigorik, chair of the W3C Web Performance working group.
Other than that there are some older docs for the Blink engine which drives Chromium. It's much more low level and hard to follow though.
The Navigation Timing spec is good for building an understanding of the major events that go into a page loading and creating HTML elements. It's not the whole picture but gives the timings for navigation and DOM element events.
Udacity has some really awesome free courses from Google devs about this: Website Performance Optimization and Browser Rendering Optimization
Nice! I'll definitely be doing this course; the previous one about optimizing sites to load fast (critical rendering path) was extremely well done. 
I've been doing a lot of work optimizing an HTML5 webapp for an embedded platform lately, and it's been extremely challenging. So much information about the guts of browser rendering engines is either buried in mailing list posts or not there at all.
FWIW, I found Safari to have some very nice tooling for optimizing animations. In particular the Layer Panel (shows you the memory usage for all the composited layers) was something I miss in Chrome. I also find Safari's way of displaying how many repaints/texture uploads to be a bit nicer on the eyes than Chrome's epilepsy-inducing flashing :)
As a former game developer, I find all this stuff really interesting, and it's nice to have these kind of engineering challenges and learning to get your teeth stuck into.
This looks like the course: https://www.udacity.com/course/ud884
Blog post announcement: http://blog.udacity.com/2014/06/new-mini-course-website-perf...
But it looks like this was made available in June.
The Critical Rendering Path