"I'm unsure of whether the remaining 90% is due to DOM interaction, rendering, or just perceived crappiness but it exists nonetheless."
A mix of all of that. For the DOM part Mozilla is developing new bindings (called Paris bindings) to close the performance gap compared to the competition [1]. Johnny Stenbeck has written two articles which give an interesting insight into past, present and future DOM bindings in Gecko [2][3]. Azure is Mozilla's new rendering API which even in its infancy showed some promising performance improvements [4][5]. Unfortunately work on Azure hasn't been progressing as fast as I had hoped. AFAIK only the canvas element is currently using Azure for rendering, the rest (ui + content) is still based on legacy APIs. On the JavaScript front there's IonMonkey, a brand new JIT compiler developed from scratch [6]. It's still in ongoing development and lacks many optimizations so right now it's slower than Mozilla's current JIT compilers in many tests [7].
A mix of all of that. For the DOM part Mozilla is developing new bindings (called Paris bindings) to close the performance gap compared to the competition [1]. Johnny Stenbeck has written two articles which give an interesting insight into past, present and future DOM bindings in Gecko [2][3]. Azure is Mozilla's new rendering API which even in its infancy showed some promising performance improvements [4][5]. Unfortunately work on Azure hasn't been progressing as fast as I had hoped. AFAIK only the canvas element is currently using Azure for rendering, the rest (ui + content) is still based on legacy APIs. On the JavaScript front there's IonMonkey, a brand new JIT compiler developed from scratch [6]. It's still in ongoing development and lacks many optimizations so right now it's slower than Mozilla's current JIT compilers in many tests [7].
[1] https://bugzilla.mozilla.org/show_bug.cgi?id=580070 [2] http://jstenback.wordpress.com/2012/04/07/history-of-mozilla... [3] http://jstenback.wordpress.com/2012/04/11/new-dom-bindings/ [4] http://blog.mozilla.org/joe/2011/04/26/introducing-the-azure... [5] http://www.basschouten.com/blog1.php/comparing-performance-a... [6] https://wiki.mozilla.org/IonMonkey [7] http://arewefastyet.com/?a=b&view=regress