At the end of June the Firefox desktop team held a Performance-themed work week Toronto, which included representatives from the Performance team as well as some other teams (QA, automation/testing, project management, etc.). During the week a bunch of us got together and held a little “intro to Firefox code” session – partially for the benefit of a new hire on our team (Steven MacLeod), but also partially because it can be fun to share different perspectives on how we understand Firefox. This was a group discussion, but a lot of it involved me giving my perspective on how Firefox front-end code works at a high level, and how it all fits together. We also went off on a few tangents discussing Mozilla development in general.
mconley was kind enough to take some notes from the session on an etherpad (UPDATE: Etherpad is having issues, here’s an alternate link). These could serve as a good base for an MDN article, or perhaps something similar to https://wiki.mozilla.org/Gecko:Overview.