Shadows is the first thing to turn off to improve performace.

You have to upgrade your video card is about all you can do.

I have 6 computers with 1 character on the main and 5X7 on the others so i can run my main full everything and the other 5 computers are about middle/low effects.

Even if I had one computer I would run fullscreen as you dont have to render more then one character at a time then, but most everyone else runs tiles, I just think that puts to much strain on your video card. Of course I use dated 9800 (nivdia) video cards ....