These are problems I never had prior to patch 1.8 or Dlc's and occur anytime anywhere in the game world.

- Frequent screen tearing.

-Frequent crashes/freezes on loading screens.

-Npc's repeat lines or get stuck saying lines in a loop until you leave and come back.

- Torch lighting effects only display properly when you are close to them and pop in not fade in realisticly.

-World seems less stable, more lag, freezing, tearing, pop in.

Hope this helps towards patch 1.9 prior to Redguard.

Since installing the DG DLC I have had to disable autosaving and clear my system cache everytime before i log onto to Skyrim, about 2-3 times a day. Since i have been doing this gameplay has been much better. I was having many of the same problems you just described, mostly freezing.