First of, this is something that has worked for me in the past, it may not necessarily work for you.
1- Set the overall graphics quality to fast
2- Set the texture quality to 16 meg. I do not personally recommend setting it to compatibility mode, as it will cause other problems. Trees and the such wont be fully rendered, which may make traveling harder, since you may not see something that blocks your path.
3- make sure, environment shadows are off.
4- uncheck all the boxes in the advanced video options. Use high resolution font, has no bearing.
5- bring all the sliders in the advanced video options to their full left.
6- lastly, this one can be used even if your settings are set to full (like mine are usually). When you are in a area that is usually very jumpy for you, example the crimson eagle's memorial. Pan your camera to a 45 degree angle. What that does, is that the video card doesn't render what is not visible to the camera, so it gives a better frame rate. The closer the camera is to your character the better.
This may not be full proof, but has helped me in the past when I had a much weaker video card. I'm using a nvidia 8600 right now, and I am able to play mostly on full graphics, well when there is not 20 fully buffed out people around me with lots of effects on them :p. Even then, tilting the camera to a 45 degree often helps me.
Hope that helps those that crashes in those swamps tileset, or have problems enjoying the game on full graphics.
