What every developer should know about rendering 101 - High level but clear. This is a baseline for what we should keep in mind to avoid jankiness.
HTML5rocks - Tutorial on how various browsers handle rendering. Includes discussions of the parsing and lexing as well as the internals of various browser implementations.
In Depth Slideshow - Great in-depth slideshow that covers more than just rendering. Very thorough.
Google Developers - This covers just the rendering portion. This explains performance related issues with it.
Slideshare deck - Manish Trivedi did a nice high level look at things.