This is in a demo I converted from V2.1.4 to V3:
As you bash the ball around, you'll notice it starts to slow down. I did change the linear and angular damping to 0 (as I did for V2.1.4) but that made no difference.
As the ball bounces around the room off bricks you can see it slowing down. As long as it hits the bat, it seems ok but once it's off say the top above the bricks it starts to grind to a halt.
What am I doing wrong?