There are a couple things that you can do to increase frame rate in the game.
1. Adjust the tactical game speed
- Tap the "START" button on the controller
- Select "OPTIONS"
- Select "GAME"
- Adjust the "TACTICAL GAME SPEED" slider to to the right for maximum game speed
What is tactical game speed?
Answer - It is the speed the game runs during combat. So this adjustment will increase the speed at which the game runs.
2. Perform System Maintenance on your 360 by cleaning your HD cache
a. Locate the System section of the Xbox 360 Dashboard.
b. Select Memory, select Hard Drive, and then press Y to view the device options screen.
c. On the Xbox 360 Controller, press the X button, press the X button again, press the left bumper, press the right bumper, press the X button, and then press the X button again.
d. You will be prompted to confirm system maintenance, select Yes by pressing A.
MS Support Page
Every little bit helps!