Apple admits to slowing down some older devices

A customer tries out a new Apple iPhone 6S at an Apple store in Chicago. Photo: Kiichiro Sato / AP

Apple's move to deal with old batteries has thrown gasoline onto a long-simmering debate over why iPhones seem to slow down significantly as they get older.

What's happening: The company said Wednesday that, under specific circumstances, it does reduce performance on devices, but said the move is necessary to avoid total device shutdowns. The acknowledgment came after a Reddit discussion was followed up with a benchmarking firm confirming something amiss in its testing.