If one phone becomes too slow, do this to make sure you maintain you RAM{random access memory}
limit widgets and live wallpapers
disable applications. To do this go to settings>>app or app manager>>all and select the one you want to disable
Disable animations. To do this, first go to settings>>about phone>>then tap the build number about 7 times until notified that you have become a developer. Go back to settings and scroll down to developer options. Next go into the drawing section and turn off the following options
>window animation scale
>Transition animation scale
>Animator duration scale
limit widgets and live wallpapersdisable applications. To do this go to settings>>app or app manager>>all and select the one you want to disableDisable animations. To do this, first go to settings>>about phone>>then tap the build number about 7 times until notified that you have become a developer. Go back to settings and scroll down to developer options. Next go into the drawing section and turn off the following options>window animation scale
>Transition animation scale
>Animator duration scale