How does Gecko (or any other layout engine) render a document/page?

It was kind of hard to go through Gecko's documentation to see how it renders a web page.

I'm doing some performance analysis for my projects across the leading browsers to see how to improve response time. I am aware of optimization techniques out there but I don't really understand their basis — which I believe would be resolved if I knew how browser engines do their th开发者_运维知识库ing.

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I gave a tech talk on material that might be useful a few years ago. It wasn't the best of presentations, but I think I did manage to convey some useful information despite that. (Slides at http://dbaron.org/talks/2008-11-12-faster-html-and-css/slide-1.xhtml or http://dbaron.org/talks/2008-11-12-faster-html-and-css/master.xhtml.)