"I assume it's because a lot of people have older Android phones with weaker hardware"
this can't be the reason, because all iOS devices are a way older than the old android devices. Look at the "new" iphone 6, it has tech specs from the nexus from 2012. Same thing with the othe rapple devices, they have all older hardware, apple users pay for the logo, and the name, not for a good hardware.
btw: When I develop a new game for android, and optimize it for a lower mid-class device like as the asus memo hd pad 7 WITH highest energy-save-mode(~half power), then it works everytime on each iOS devices without framedrops(lags) when I port it to iOS
btw2: maybe is there also an device detection activated, so that the game can determine your device via android and set the best graphic settings.