From The Botanist Game Blog
"One major weakness of Phaser’s mobile performance, though, is its default camera following mode. The camera follow mode pans the camera smoothly to follow the character, which is beautiful visually but also forces a full redraw on every frame. This works fine on desktop, but mobile browsers tend to struggle, especially given patchy support for WebGL.
My solution is to write a more efficient following mode for mobile devices. Rather than redrawing on every frame with smooth scrolling, we should only redraw once if the player is at the edge of the screen."