With the release of iOS 8 and the new iPhones, the Apple iPhone 4S has fallen down to become the oldest iPhone to support Apple's newest mobile OS. However those who own the iPhone which debuted in 2011 should probably avoid upgrading to iOS 8 as it seemingly causes severer performance issues for the device.
As Apple continues to upgrade iOS, their older devices are continuously left behind, allowing only the top of the company's line to breeze through the newest iOS releases. On top of that Apple also makes several tradeoffs on features due to hardware restrictions on older devices.
Because of this, the iPhone 4s is missing a number of features like Touch ID, AirDrop, Handoff for applications and support for OpenGL ES 3.0. The iPhone 4S is currently the slowest iPhone in the market, with 2.4GHz-only 802.11n Wi-Fi, no support for LTE connectivity, and its Apple A5 chip that has 25% of the raw performance of the A7 used on the Apple iPhone 5s. The iPhone 4S is also the last iPhone to feature a 3.5 inch display, as Apple has now transitioned to much larger screen sizes.
Because Apple has clearly moved on to greener pastures, iPhone 4S users will find their devices no longer get a premium experience on the iOS platform. In fact the iPhone 4S can take as much as 50% more time to perform as task on iOS 8 when compared to iOS 7.1.2. ON top of that, the iPhone 4S seems to have a habit of dropping frames during animation, which gives the device the impression of being slow.
If you have an Apple iPhone 4S, your best bet might be to wait for for Apple to release an iOS 8.0.1 update which will hopefully fix these performance issues. Meanwhile anyone planning to purchase a new iPhone, should definitely consider investing in something better than an iPhone 5 or even look at Android or Windows Phone as a viable option.
source - ArcTechnica | RedmondPie