PINPOINT THE PROBLEM
It could be an app, multiple apps, the storage or the system itself slowing down your device. Before you either fix your device yourself or give it to a technician to help you fix it, it is important you try to identify what the problem is or might be, and what the problem isn’t. With this knowledge, the problem will be easier for you to solve on your own or, if you decide to give the phone to a technician instead, it will help you avoid being cheated.
A diagnostic app can help you pinpoint the problem causing your device to run slowly. Phone Doctor Plus and Z-device Test are good diagnostic apps to consider. You can find them on Google Play Store. Some Android devices come with diagnostic apps, like Samsung with the Samsung Smart Care app. In this case, you can take advantage of that rather than downloading another from the Google Play Store.