Try turning off other graphical features in the settings file (e.g. trees, water stuff like that). I feel like your computer is a bit... out of date. But the 2gb fix should have worked. Check to make sure it saved right while you are at it.
Admittedly, it is a bit out of date. However, I have yet to encounter any trouble with any other games I play Skyrim, Guild Wars 2, Age of Conan. It still runs all those games well, so I have put off building a new one til it was kind of necessary. Maybe it is that time.
How can I check to see if it was "saved right"? I have kind of felt all along that this was a result of a corrupted save file.