I can't promise that you won't ever have choppy CSS animations anymore, but it is currently the case that the desktop version of the "new Firefox", so the upcom

I can't promise that you won't ever have choppy CSS animations anymore, but it is currently the case that the desktop version of the "new Firefox", so the upcoming Firefox 57, ships with a new, written from scratch and highly parallelized CSS engine (Quantum CSS, or also called Stylo), whereas the Android version will probably get this with Firefox 58, maybe 59.