Last week I followed this advise in OP1.
I backed up all important personal data from my Ext SD onto my laptop then formatted it. After restoring the data to my Ext SD, I then backed up all important data on internal storage to my Ext SD and wiped all data.
Having restored root, I then flashed the ROM & Gapps, restoring Apps and Contacts from the TIBU backup on the Ext SD.
Only 3.5GB of my internal storage is now being used.
The device is far smoother and I have had no fc or reboots or heavy battery drain since.
Sent from my GT-I9300 using Tapatalk