My wow keeps freezing on headless horseman and now in naxxramas?

Hey guys, as of patch 4.0 my wow was working fine, little laggy on 25mans, addons are nonexistant. When they released headless horseman this year, I wanted to try to get my mount, so I dungeon finder'd it and got into one, someone clicks the pumpkin my wow froze, I found the solution to be standing at least 100 yards away from it when it's clicked to work, that is not my main concern. Now I was trying to do the weekly, and I got summoned in, within 3-5 seconds, my wow froze, so i opened task manager and ended the process, reopened it and got back in, and yet again 3-5 seconds it froze again, and I was kicked for my wow freezing. Any comments would be helpful, please try to help this because I'm uming it's going for all of my raids as well.