[pcwalton]

Just using the GPU isn't enough. On iOS and macOS you have a compositor that has exclusive access to the display that native widgets will use. If you do all the rendering yourself on the GPU, you'll incur an extra hidden full window blit on the compositor side, which is definitely noticeable, especially in power efficiency.

[Hixie]

If it is noticeable, please do file a bug with the details of the device on this you're seeing the problem. https://github.com/flutter/flutter/issues/new?template=perfo...