Apple Inc recently admitted that older iPhone models were intentionally slowed down in an update to avoid a sudden shutdown that used to be a major problem in iPhone 6, iPhone 6s and iPhone SE. The Cupertino tech titan later rolled out a similar update to iPhone 7 devices. Although the move was made to improve the user experience, not all iPhone owners were happy with the fact that Apple hid it for years.
Tonnes of people might not be certain whether they have been affected by the said throttling of performance or they have dodged the bullet. Either way, you will need to have your iPhone tested.
Geekbench is processor benchmarking program that can assess the performance of your device and it is available for iOS. This app, however, is not free.
Fortunately, options are available in the market that will not charge you even a single cent. The Battery Life app is free to download and is a good alternative to put your device to test. It helps you to monitor your iPhone battery's raw data as well as the level of wear it has suffered through years of use. On top of that, the app will let you evaluate your options and choose which direction you should be moving forward once you know them.
Apple previously acknowledged using codes built into the iOS codebase from iOS 10.2.1 and later versions to identify the performance and state of the iPhone 6, SE, 6s and 7's internal battery. This way, the company is in control of the devices' performance according to battery health and capability; otherwise, iPhones might shut down out the blue or act in mess.
You can download Battery Life for iOS from the App Store for free.
In the meantime, if you are no longer happy with your phone's performance, you can actually have its battery replaced so you have a charge and discharge cycle in full circle.