My Samsung Galaxy S3 Neo i9300 became slow and started freezing more frequently.
Based on the 
post I tried to 
clear the cache partition as instructed in this 
video:
Power off phone (hold power button, choose power off).
Press and hold following buttons together: 
Volume Up, Home, Power.
Hold all buttons until phone vibrates and shows message 
recovery options.
Release 
Power button.
Choose 
wipe cache partition.
Wait until message 
Cache wipe complete.
Choose 
reboot system now.
You are done.