No don't delete it, it is difficult to edit/delete as the browser will re-write it immediatly. Have you any browser extensions installed? AdBlockPlus didn't work after PR.12, no idea if it will work with PR1.3 It didn't cause your problems just made the browser realy slow. If the problems occured with PR1.2 and you did a restore then the problems could be in your settings. If all else fails re-flash and restore all but your settings.