Not slow
It takes about 2-2.5 hours for an iPhone 13 to fully charge wirelessly. The iPhone 13 mini has a 2406mah battery and takes about an hour and a half to fully charge. The iPhone 13 pro has a 3095mah battery, which takes about an hour to fully charge. The iPhone 13 pro max has a 4,352mah battery and takes about 45 minutes to an hour to fully charge.