I'd be interested in other resources for this too. The best I can think of is Udacity's Web Performance Optimization class[0]. 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[1][2].

The Navigation Timing spec is good for building an understanding of the major events that go into a page loading and creating HTML elements[3]. It's not the whole picture but gives the timings for navigation and DOM element events.

[0] https://www.udacity.com/course/website-performance-optimizat...

[1] https://www.chromium.org/developers/the-rendering-critical-p...

[2] https://docs.google.com/document/d/1wYNK2q_8vQuhVSWyUHZMVPGE...

[3] https://www.w3.org/TR/navigation-timing/#processing-model

Here is are a couple:

https://developers.google.com/web/fundamentals/performance/r... https://developers.google.com/web/fundamentals/performance/c...

Would be interested to hear of more also.

This one is quite good. I posted it to Hn 6 years or so ago but it didn’t get upvotes:

https://www.html5rocks.com/en/tutorials/internals/howbrowser...

How much of it is relevant 8 years later?

Nearly all of it

This series is also quite good, a bit more modern:

https://developers.google.com/web/updates/2018/09/inside-bro...