I've had the same problem but I don't think it's limited to iOS 9.3. Search the apple communities, tons of people have the same problem, as did I. What I did to fix it was restore a fresh copy, not a backup, of 9.2.1 and uninstall booking.com and Wikipedia. These apps seems to be a big part of this problem. Deleting the apps won't do it, must delete and restore phone as new. Hope this helps