Apple says it's true, your old iPhone is getting slower. The company confirmed Wednesday that older models get slow with age. Apple says the "slowdowns" are a deliberate effort to keep older phones running longer as the battery wears down. A statement from Apple says lithium-ion batteries have a low charge as they age, which can result in the device unexpectedly shutting down to protect its electronic components.
The company said last year it released a feature for iPhone 6, 6s and SE to help avoid such blackouts. Some iPhone 7 units will also be experiencing the throttling too. Cold weather also affects the performance of the devices.
While iPhone batteries aren’t easy to replace, if you have an older phone and put cash into a replacement, the performance will return to normal.
Source: The Verge