Phone extremely slow

Hi<br> <br> just recently purchased couple of Samsung J1 (SM-J100H) phones.<br> <br> i should say that it is by far the worst phone you guys could ever come up with. From the first boot of the phones, things were constantly slow to happen. There were stutters throughout the interface, with animations not at all smooth most of the time. Apps were slow to launch as well, though this was more an issue on some of Samsung's inbuilt apps rather than third-party ones.<br> Not even cache / memory cleaning app can help with the \slowness".<br> <br> what happened ?"""