After iPhone users expressed online that their devices seemed to be slowing down, Apple told CNBC that the phone's battery is the reason.
"Lithium-ion batteries become less capable of supplying peak current demands when in cold conditions, have a low battery charge or as they age over time, which can result in the device unexpectedly shutting down to protect its electronic components," Apple said.
To compensate for the battery, Apple confirmed it put algorithms in place to keep the phone running efficiently and to "smooth out" power requirements.
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The slow-down feature was introduced for iPhone 6, 6s, SE, and 7, and Apple will add it to "other products in the future" too.