In accordance with this topic:
Firefox 38-40 SMIL problems - very slow speed (resolved in FF version 41 from 22.09.15)
and this
SMIL support was not removed from Chrome but was replaced with a Polyfill. Eric Willigers has created a SMIL polyfill implemented entirely on the Web Animations API. You can find it here: https://github.com/ericwilligers/svg-animation