This is a RAM issue and lost contacts issue (contacts not saved under Google). The log of text messages with all contacts, since start, is all, still there. My Android version is 4.2.1. I have had 3.5 GB available on the internal storage and only 170 MB on the device memory; I was under the impression that pictures and images since they are stored at the internal storage, they do not affect the processing (is that called RAM same as in PCs or not?) speed, but that was wrong. I have moved all pictures and videos from phone to my PC to make more space but after having moved all the pictures/videos, on day before I have lost all my Phone Contacts! The speed of navigating and of using the dialer and of Contacts (these apps were worse affected in terms of speed) and even the battery life has improved a lot, yet I still need to find more space (by emptying the SIM card), but I await to take the phone to a repair centre to be seen first.
400 or so contacts were saved under 'Phone Contacts'' and they are all gone. Since 350 of my Contacts were saved primarily under Google (Gmail), I have not lost all Contacts but another I called Samsung Support service and they advised me to visit a Geek Squad Carphone warehouse which is authorised to service Samsung-Android devices. Should I do this first to be on the safe side, or should I download the Dr. Fone for Android app and try to bring back the Contacts? Does anyone have experience with Dr Fone? http://www.wondershare.net/disk-utility/recover-contacts-from-samsung.html?gclid=CJTkyPLpwboCFfHKtAodpngArA