Unhappy koodo Samsung Galaxy SIII (SGH-I747M) going nuts help

Ok so everyone says this is a great phone, but at the moment I really miss my S2 International

My S3 is constantly freezing up, toggling wifi, just all around slow. Like I can go make a pot of coffee half the time while im waiting for an app to load.

Some info on what im using. Phone was koodo and is now unlocked and running on fido. I got phone second hand and when booted into recovery it shows dead droid (phone is not rooted or anything to my knowledge, verified with root checker) my main apps of use are chrome youtube tasker utter bbm and facebook. So I am very frustrated as my S2 seems to have been twice the phone this is. Please help me fix this as it cant be right!