I was able to solve our problem
I have galaxy S3 and I take care of it I don't download any application and I own it for 9 months now, I don't use an SD card and for some reason it started to become VERRRY slow and sluggish. I didn't react to it as I thought may be my phone is just passing thru a phase
Suddenly it started to freeze and it worsened and worsened, until I decided to:
back up my data (which took almost 4 restarts)
delete almost 5Gb of memory
remove live wallpaper
remove photo widgets
remove unneeded apps (ex: games, tubemate, flashlight...)
restarted my phone...
and now it's cured
I believe it's a memory problem because now it's back to normal THANK GOD!!!
hope this helps....