回答“Feasible to upgrade processor in iPhone 4?”No. You can't. Sorry. I was thinking exactly the same, and, i wrote this comment ON MY LAGGY IPHONE 4. But, to the point. If you want a faster phone, you could try to turn off your motion graphics, and increase contrast. Also, turn off background app refreshing. It helps. And, if you really want to get a faster phone, you may risk a A7 processor and edit the whole board to the pin layout for the iPhone 4. But its not worth of it. Im looking for some money to buy a 5C or 5. But yeah, i know how you feel holding the slowest phone on the world(not really, just a slow one). Sorry, the tips i gave you are the only ones that give effect, espeshially for gaming.