It's simple.Just make sure you have enough card space,and close all other applications before running the game.
Don't worry about the quality.As long as you have Definition:On,it still has good graphics.
The most important here is low settings even on the most powerful systems.Make sure the number on the bottom is green and far away
from the max MB capacity.Example I play both IV and EFLC with 202/538MB which is just perfect to play the game without lag.
If you reaaally want high settings,use a game-boosting software.But all they do is close other applications,nothing more.
Hope it works...