Lagging, Freezing, Dropping Call

My mom's phone screen freezes/lags. She has to press an icon a few times in order for it to start. When she clicks on an icon, it takes about 5-8 seconds on average for it to open up. In addition, random freezes causes her calls to drop. She has had the phone for 9 months and doesn't have any background apps outside of the factory default. She does only have 133 mb of storage left out of 8 gb, however.

Anyone have any suggestions or fixes outside of resetting to factory settings?

P.S. When I try to access camera or anything in the settings, I get sent to homescreen/desktop.