Any shade issues?

A cool summer can do that also.

Is it getting enough sun? No insect damage? A soil test is never a bad idea.

The Bermuda in South Georgia has slowed some due to the cooler weather but not as much as you are describing, especially the summer part. I hope you don't have my problem--cutworms. It will seem like your grass is growing slower because the worms are cutting the grass for you when there are not enough numbers to wipe out the entire area. I currently have a cutworm infestation. I am also in South Georgia and have finally given up after trying everything the pundits have suggested. I've used poison, bt, multiple applications, sprayed at night- everything until i've just given up and turned the yard over to them. Cutworms are hard to identify since they hide in the day and come out at night. One way is to check for moths in the yard and especially in the flower beds. They love to lay their eggs on plastic columns and such. These eggs become cutworms. If you got'em forget it and go golfing. You might try centipede, the centipede yards around here are flourishing.

All, thanks for the replys. My yard gets plenty of sun with very little shade. Could be insect damage but the vast majority of the grass looks healthy, it just has grown so slow all summer. Even awaiting 5 to 7 days to cut it has been hard because I am removing so little grass it is hard to determine what needs cutting and what I just cut. I guess I was used to the bermuda I had in SC where if I waited a week the lawn mower would bog down trying to get thru all the grass it was cutting.