Theres a couple things that cause stuttering: the first time a sound is played it is decoded, and the first time a particle effect is seen its shader is compiled (snow and flame particles).

The bug your describing with the trees I think is just a by product of my having not implemented proper 'pixel perfect' camera positioning, ie: the trees are being rendered off center from a pixel so they look glitchy, while the character is always at the same position on the screen so doesnt look glitchy.

I'm suprised your ipad pro has the above sound/shader issue as noticably... Shader compilation is also pretty brutal on windows.

Thanks for the feedback and bug reports.