For anyone else having performance problems with iPad, I wasn't able to touch things on the screen. Deleting the Sonos app solved these problems after I saw the Sonos battery consumption at 25% - this means its running away with the background process and kill my iPad.
Very annoying, could not even read a kindle properly much less use my Pencil. Sonos quality continues to go downhill, will they survive the competition from Amazon, Apple and Google ? It seems unlikely with problems like these.