Go to external camera, or periscope. If the card is too weak there will be frame drop and u will see that coursor move is not smooth. Go then to video options and try off/on different effect. Game will change it at the moment and u will see how it impact your cursor movement and what effects affect fps most. That way it is easy to find some optimal video settings. For example my radeon x1900 only valumetric fog is frame killer rest i set up to the max
Hope this helps players to quick find optimal video settings