This solution was offered by
EA Tech Support when a member of our forums wrote to them...
To solve this issue, please set your XBOX to the correct video mode:
-Power on the XBOX without a disc in the disc drive
-Select "Settings" to go to the Settings menu
-Select "Video" to enter the Video Settings menu
-Select the top option "Normal" from the menu, also, if the option is availible, enable "480i" and disable all other numeric settings.
-Press the B button until you are back at the main menu.
-Now that the Video settings are properly set, launch NCAA Football 2005
-At the NCAA Football 2005 Main Menu, select "MY NCAA"
-Select "Settings", then enter "Visual Settings"
-Once in Visual Settings, change the camera view from the default
"NCAA" to the "Classic" camera view.
This should clear up your slowdown issues.
Note: If you are playing online, and your opponent has incorrectly set their Video and Visual settings, you may notice the same slowdown. In these cases, it is best to either find a different opponent, or explain that they should properly set up their Video and Visual settings.