Pretty weird when the game run damn smooth on browser ( and as APP too, I assume )
Did you use built-in physics or adding library ?
Apart from the rendering engine (HeapsIO), everything else is homebrew, including the physics :)
The source code is available here: https://github.com/deepnight/ld48-NuclearBlaze
And my physics engine is explained here: https://deepnight.net/tutorial/a-simple-platformer-engine-part-1-basics/