Getting good performance out of iOS was a major focus for v0.8 - thus the shady dom. They got >5x faster performance: https://blog.polymer-project.org/updates/2

Getting good performance out of iOS was a major focus for v0.8 - thus the shady dom. They got >5x faster performance: https://blog.polymer-project.org/updates/2015/03/27/why-0.8/ https://blog.polymer-project.org/updates/2015/03/27/why-0.8/