As we age iPhones, we expect the root performance to decline - it's something generally accepted about all smartphones, tablets, or anything else that uses rechargeable batteries.
The more battery that is charged and discharged, the shorter the battery will cost a single charge. However, what we may not always expect is the old iPhone battery that affects CPU performance. However, it came after a report last week suggested that iPhone 6s with old batteries could see performance improvements when batteries are replaced.
This, and a long reddit thread with a surprising number of comments, made Geekbench founder John Poole wonder and since then he has posted on this issue. With some users noting that the Geekbench score is reduced while using older batteries and then increases after the replacement of the battery, there is definitely something wrong.
While Apple recognizes that there is a battery issue with the iPhone 6s up to the point of releasing software updates to address it by changing the CPU speed dynamically depending on the amount of remaining battery power, this has the potential of leaving the user. with devices being sub-optimal, often without their knowledge of why. This, as Poole points out, can see users switch devices faster than needed because their iPhone is considered to show performance issues.
Note :If the performance decline is caused by a "sudden shutdown", the user will experience a performance loss without notice. Users expect full performance, or reduce performance by noticing that their phones are in low power mode. This improvement creates an unexpected third state. While this situation is made to mask the lack of battery power, users may believe that this slowdown is due to CPU performance, not battery performance, which triggers Apple slowly introducing the CPU. This improvement will also cause users to think, "my phone is slow so I have to replace it" instead, "my phone is slow so I have to replace its battery". This is likely to fit into the "planned obsolecense" narrative [sic]
As the last line disappeared, many people already believed that Apple paralyzed older devices in order for users to upgrade faster than usual. This news will be music in their ears and will certainly only reinforce that belief.
Also related to these findings is the developer of Guilherme Rambo's discovery of the "powerd" process introduced in iOS 10.2.1, which controls CPU performance, and most likely what is responsible for mitigating it in cases where deteriorated battery performance is detected.