When watching www.evolutionoftheweb.com it is very janky when the animations are moving while it is very smooth in Chrome. I have cc'ed heycam and bbirtles because there is a big svg part of the site so not sure if it is layout and the issue is svg.
Yup, the animation (after you click "Explore") definitely looks jankier on Firefox Nightly than on Chrome dev channel for me. It's particularly bad if my window is maximized. (Profiles below are with maximized window.) I'm using 64-bit linux Nightly 43.0a1 (2015-08-19). Profiles of that "explore" animation: e10s disabled: http://people.mozilla.org/~bgirard/cleopatra/#report=bdf1b92693d1a4349710bef0aa43354d12cff0fa e10s enabled: http://people.mozilla.org/~bgirard/cleopatra/#report=29ee52c216bee9fe490a1b5ded3622ef89cc7e77
Turning on paint flashing it seems like we're repainting a lot more than Chrome, particularly the tilted background part. Perhaps it's too big for us to layerize.