It depends on "-a" mode. Right now "-a 1" means max hashrate but more power consumption. "-a 2" means less power consumption but a bit less hashrate. "-a 3" mode is for 6xxx cards.
To get max hashrate for different cards I had to add "-a 4" mode and also add "-h" option that sets number of hashes that GPU handles during one round. So now it depends on GPU what "-a" mode and "-h" option are the best. In some cases you will get more hashrate at same power consumption, but sometimes it will increase power consumption. In v8.0 you have to spend some time to get best speed, but for some cases speedup is very good, I got the following results after some tuning (compared to v7.0):

270x card: 19% speedup.
280x card: 7% speedup.
290x card: 1-2% speedup.
6950 2GB card: 3% speedup.

I need to finish a special "calibration" mode that helps to find best "-h" option value, and finish some other things, so it will take a couple of days to release new version.