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.
They are working on that! But I guess there's the old trick of having a 'visibile' level at loading time that has all the shaders and variants in it so they get pre-compiled.
Yeah I have a node for Godot that does that. I think I'm going to use CPU side stuff for the particles instead of shaders instead... And the audio you can load ahead of time as well