Your Android phone was fast when your bought it then with time it became slow. This is a common problem. Below is a guide to make your phone fast again.
1. Free up some space/uninstall useless appsAll those photos you've taken and apps you installed can slow down your phone if it's running low on space.

You can check how much space you have left by heading to the Storage section of Settings. One of the easiest ways to free up space is to tap Applications and see which apps you can uninstall.
2. Disable widgetsAll those widgets running on your home screen may be useful, but they use a lot of memory which slows down your android phone.

If you have any widget you don't need, delete them.
3. Reduce launcher AnimationsDepending on the launcher you are using, you may find that there are various animations and special effects in place. These may look great, but they can also slow things down.
4. Close down apps and free up RAMMulti-tasking several apps makes it easy to switch between different tools, but there can also be an impact on performance. You can quickly close down any apps you are no longer using by calling up the running apps list – press and hold the home key and then swipe away any apps you want to exit.

Terminating unused apps and freeing up RAM will help speed up your device.
5. Reboot you DeviceA quick and simple fix to speed up a slow device is to restart it.

This can clear you Android Cache and stop useless tasks from running.