Many Galaxy s3 users have reported that their phones freeze, lag and crash all the time making the phone impossible to use it normally.
But there is a fix about freezing problem on the Galaxy S4.
First of all you have to download Dummy File Generator here
This software can output a dummy file in the storage.This means thay you can create a state (memory full) status of the lack of storage capacity of the terminal.The output destination can be selected either the “External SD card “, “Internal SD card”, “Internal memory”.
Once you have installed this app and generated a dummy file, your Galaxy S3 will have a less lags and freezes.