Read everything about Construct 2 regarding performance. Some of the things you find about performance issues may be back in 2012 and as time goes on, more powerful devices come out and this means better performance on mobile. It literally does take time for performance to get better and for Construct 2 to be more capable of creating better mobile games.
Even so, using Cocoon.IO and optimizing your game very well, will lead to a "good" experience.