Walton,
I am not sure why you aren't getting the full frame rate. One thing to try would be decreasing the exposure time.
I have attached my own version of the ICD file for the ES310T. I use this for one of my products. I added a section that maximizes the exposure for a given frame rate. If you are in MAX and you select "Max Exposure" for the camera mode, you should be able to get the full frame rate at 125 FPS.
Bruce
Bruce Ammons
Ammons Engineering