iOS 8 on the iPhone 4S: Performance isn't the (only) problem

New OS wants screen space and processing power that the old phone doesn't have.

The iPhone 4S Camera Upgrade Explained

iOS 9 on the iPhone 4S: A stay of execution, nothing more

Apple hit with class action lawsuit over iOS 9's performance on older iPhones - 9to5Mac

iOS 8: 35 Problems and Bugs and How to Fix Them

How to Get Better iPhone 4s Performance on iOS 8

Farewell iPhone 4: No iOS 8 upgrade for you

iOS 8 on the iPhone 4S: Performance isn't the (only) problem

iOS 8 Hinders iPhone 4s Performance By A Huge Margin

AT&T iPhone 4S review: AT&T iPhone 4S - CNET

iPhone 4S call audio issues to remain with new iOS 5.1 build

Forget the iPhone 5, Apple's next phone is the iPhone '4S