I recently upgraded from an iPhone 15 Pro to a regular iPhone 16 and transferred my data from the old phone about 20 hours ago. The new phone feels unusually sluggish, with noticeably choppy animations and a frame rate that makes it seem as though Low Power Mode is enabled.
My iCloud data appears to have finished syncing, and I left the phone switched on and charging overnight. During setup, it initially had trouble connecting to Apple's services and rejected my Apple ID login, although restarting the phone fixed that.
I previously used a family Apple account, but I now have my own Apple ID. Some apps that were originally downloaded with the old account appeared greyed out after the transfer, though I was able to reinstall them using my current account.
Could the account history or incomplete background setup be causing the performance problems? Is there anything I should try, or is this simply because the regular iPhone 16 has a lower refresh rate than the iPhone 15 Pro? I'm keeping the old phone available until I'm sure the new one is working properly.
2 Answers
A fresh transfer can make an iPhone feel slow while it finishes indexing Photos, apps, and other iCloud data, so leaving it connected to Wi-Fi and power for a while and then restarting it is worth trying. The old Apple ID should not affect the phone’s frame rate. Apps that were originally obtained with that account may need to be deleted and reinstalled using your current Apple ID. Keep the iPhone 15 Pro untouched until you’re satisfied everything has transferred correctly.
There may be a hardware difference rather than a fault. The iPhone 15 Pro has ProMotion, which can refresh the display at up to 120Hz, while the regular iPhone 16 uses a 60Hz display. Scrolling and animations can therefore look dramatically less fluid on the 16, especially immediately after using the 15 Pro. It can feel like Low Power Mode even when no setting is enabled.
That’s disappointing—I didn’t expect the difference to be this noticeable. It really does feel like the 15 Pro is in battery-saving mode compared with the new phone.