According to the iPhone 6s user, his iPhone ran very slowly after upgrading to iOS 11, especially compared to his brother's iPhone 6 Plus, where they did some testing with running software and battery life apps.
Pass the test, he found that when the battery age of about 20%, the iPhone ran into single-core 1466, multi-core 2512; Subsequently, he changed a new battery for the iPhone, the results run into a single-core 2526, multi-core 4456 They emphasized that the results were the same whether or not the Low Battery mode was turned on during the test.
'As far as I know, Apple slows down the phone when the battery is low enough to make sure it charges properly.' (The author's idea is that when the iPhone is low, it automatically down-converts, and according to his test, Aging, it will automatically down-conversion)
I do not know if you still remember the iPhone 6s a year ago, automatic shutdown event, the beginning of the Apple iPhone 6s for eligible users to replace the battery for free when Apple said only a small part of the 6s users because of this problem has been affected.
Later, Apple pushed the iOS 10.2.1 system update, in this update added to solve the problem of uneven power supply caused by the old battery automatically shut down the problem.Apple said that this update to iPhone 6s automatically shut down the situation reduced by 80 %, iPhone 6 less 70%.
However, this test, many users linked it with the iPhone 6s automatic shutdown event, they speculated that Apple Inc. through the dynamic down-frequency approach to the old iPhone to avoid automatic shutdown.Of course, there are people think that Apple deliberately strangled the old Equipment performance. Whether for any reason, these views will certainly lead to a debate.
As of press time, Apple has not made any comment on the matter.