I&#x27;m on the Polymer team. Shady DOM is probably the biggest beef that we have with the project, but it was a very necessary tradeoff given that the Shadow DOM polyfill was just too slow.<p>Polymer can seamlessly switch between Shadow DOM and Shady DOM (though your own elements needs to be tested under both). You can still use the Shadow DOM polyfill is compatibility is a higher concern than raw performance.<p>Safari and Chrome will have native Shadow DOM v1 implementations by the end of the year, and quite possibly Firefox. If we have enough resources, we may decided to make an IE&#x2F;Edge specific Shadow DOM polyfill that&#x27;ll be much faster because it&#x27;ll path DOM prototypes rather than wrap DOM nodes. Wrapping is necessary because Safari doesn&#x27;t properly let you patch Node prototypes. If this happens, we&#x27;ll have fast and compatible DOM APIs.