| Speed tuning
One major factor of the graphics speed is full scene antialising (fsaa).
Fsaa smoothens contrast eg. a wire before the blue sky and lets the pictures look much smoother and more tv like.
Fsaa makes lower resolution look like higher resolution.
Fsaa x4 ( horizontal and vertical calculation ) needs 4 times the graphic power of a non Fsaa picture.
So while your card may display a enormous 80 frames per second at 1280x1024, when you activate fsaa (or it is on by default) your frame rate drops to roughly 20 fps (unless you have very good hardware fsaa).
A solution would be deactivating fsaa and using 1600x1200 instead.
However if your CPU is slow but your graphics card is brand new the other way around could be better.
For example you have a Athlon 800 and bought yourself a Geforce4 4200 for a resonable $170.
Then you should choose a lower resolution so that the CPU has less work to do and activate fsaa so that the GPU can use its hardware fsaa. | 
Linear Mode
