How fast is 5G speed compared to 4G? Win iPhone 12, Mobile Insider Quiz - How fast is 5G speed compared to 4G? By Mukesh Sharma - June 9, 2021 Amazon Quiz. Answer and win. A brand new iPhone 12, Mobile Insider Quiz – How fast is 5G speed compared to 4G? 2X 10X 1X 5X The correct answer is 10X. 5G speed is 10X faster if compared to 4G.