If I have a 5% download on my computer, then on a mobile it is 50% and that means you need to optimize it until I get a computer, I will have 1-2%?
yea that would be somewhere around 30-50% usage on mobile(depends on mobile now) if u got a 5% on pc... so if u get a 4% 3% on pc is good. 7-10% on heavy games pc is ok also.
however run the debug preview, and check the cpu usage estimation(estimation means it has a margin of error of 2% or so... but is a good hint on how ur game will perform on mobiles overall seeing the spikes when actions happens and such.), cause that is what matters, not the download size.
you need to check the spikes when u play the game, if it spikes over 20% on pc when u play the game u need to optimize it, usually the draw cells spike first time on update if the action is repeatable then iddles back to a average lower point, for example jumping a character from my past tests id would go from idle 2% to 10 % then if i kept on jumping repeatedly would fall down to about 3-5% usage.
u need to check the middle cpu usage mostly when u performing actions. spiking is normal as JS is meant to work like that... in a spiky pattern usage (Ashley did a blog post about this for C3).
but u need to check what is the lowest and highest and then calculate a middle ground. and try keep everything optimized to hit that mark.