I am creating really simple animation using 3DS and Mental ray.
It is a just circle that is rotated around its y-axis. The problem is that the animation is speeding up at the beginning and slowing down at the end.
The default for keyframes in 3DS max is ease-in/out.
If you open track view select the keyframes for the in/out and click the linear button you will solve the slow start/finish. You will be able to see this visually as the track will go from smooth curves to sharp lines.
It is possible to change the default but for the life of me cant remember how without a copy of 3DS in front of me.