Thank you for this Eb246. I am very disappointed as well. Not really for my phone which I am using for short and basic tasks. Even like that, it definitely is slower than before the update to IOS 11. I have asked Apple support if we could switch back. Their answer is : no, either you change the battery (their is a significative cost behind this)or you wait until a possible fix is proposed in a future update. No commitment. More important for me is my iPad Pro 9.5 which uses the same processor than the iPhone 6S I use. The same problem exists and I am not happy at all. I am using it much more than my phone, with more applications. And everything slows down as well. There are even some things from FaceBook which bug now. FB update bug? Or Apple bug ? I know this machine has not been sold massively, But still, I chose the 256 gb option and the price is high for an obsolete machine after 2 years only. I am extremely happy with the Apple ecosystem. That is why I accept the higher price. But in this case I need to use this iPad at least 2 more years. I will therefore follow this issue closely. And will post regularly here when something can be useful for this community.