mobile

I have a G3 and a mate has given me his G2 to sort out. The basic problem is it runs extremely slowly, eg you can only type 1 character every 2 seconds. He doesn't want to root it so options are a bit limited. I reset it and it was still slow, I have now flashed the latest version of lollipop (cse flash) and its still so slooooow, anyone got any ideas...? Many Thanks