• Try uninstalling the apps which are rarely used.• Also check if you
are running latest software, if not, then try updating via Smart Switch.
• Turn off Location and Bluetooth when not in use.• Restrict background
data usage and memory usage of apps...
I haven't used yet but I've heard that two software updates improved the
performance pretty much. Try updating and I'll suggest via Smart Switch.
If the problem still persist then I'll suggest to either visit Service
Centre or get replaced. There is ...