The Corgi Engine is a very fast, non-physics based controller for your player. It's mobile friendly, works well with other assets, and is basically everything you need to start creating your own 2D game right now.
Get more information about the asset over at http://www.moremountains.com/corgi-engine-best-unity-2d-platformer
Note that this demo makes use of some of Unity's standard effects (blur, bloom, etc) and that can affect performance.This is not linked to the engine's performance, but rather depends on your device and how well it handles Unity effects. You can of course turn off these purely cosmetic effects when you create your own game.