thats weird, because i tested it too on 2 phones... both got same problem
u can check it on desktop too, just open the site in your browser and scale the window down to mobile size. the browser will stutter and hang if HIDE MOBILE DIVS -> custom_1 is enabled. if its disabled all works fine. On chrome Browser both desktop and mobile hangs, Safari on mobile hangs, IE 10 stutters, Opera does not work either but Mozilla works fine! got no tablet to test but i think its the same there... a friend checked it too, same probs!
i dont want to bug you but u are the expert
so what to do? Thx for your patience!