Don't know if this has been suggested yet, but some games perform much WORSE with minimum settings than they would with medium settings. Try putting all your settings to medium and see if that fixes things, as sometimes engines have a hard time scaling back. Also, since you have crossfire, the game engine I can probably bet you 100% does not support Crossfire or SLI. Go in to your Catalyst drivers and create a new profile for the game .exe with Crossfire disabled. This also goes for people with Nvidia, disabled SLI then try the game again. There are tons of games out there with this issue so I would say it's worth a shot.