You said you used an Nvidia graphics card? right-click on your desktop and the menu should come up, click Nvidia control panel and go to Manage 3D settings and it should say preferred graphics processor, click on the drop-down box and select High-Performance Nvidia processor or whatever else it's called. I had absolutely terrible lag, so bad that if I pressed F3 it would cover up my screen until I did this. Now I run at 40-60 FPS constantly!! Hope this helps.