Thank you for your reply, I'm aware of the risk, I didn't port any game on mobile platforms yet, so I dont know how long and tedious is the process of porting the game on specific platform. I am kinda scared of the porting process when I read posts on forums, what doesn't work and what problems are in the way.
So I want to be as prepared as possible, to have a game with decent FPS, before I start porting.
Some specific percentage or probability of the speed-up would be nice, but I understand, that it isn't that easy.
Are there some do's and dont's when I want to get as fast port as possible, or which mobile platform is easiest to port? I don't need performance guidelines, that is something I already studied.