if its touch, im guessing its mobile, if it is mobile then performance varies a hell of a lot between them, a couple years old device will run a simple unity scene at 35 fps where as the latest ones can run a large complex scene at 60 fps
loading is about memory, you might not have enough ram or your textures maybe huge, loading level has to do a lot of other things than just load assets, has to reset stuff, make sure theres nothing left behind from the old scene etc.
try to do as little level loading as possible, if its menus, make lots of menus in one level and animate that one level turning stuff on and off, otherwise you will have to put up with the loading times.