I'm on a MacBook Pro running windows 7 (lol)...so I have a Geforce 320M and 4 GB RAM. I have never ever had problems like this with sins and I've been playing for years so it might have something to do with the new effects. I usually play everything on highest and bump detail on high. This has always worked out. And I've played a few Rebellion games with no issues, this is the only game that had them.