in Court01\Court.ini , so far, you could lower HiDeceleration to make the court feels more slippery.
Now, from Build 85, you can also lower CounterBalance, which alter the left/right speed conversion. The lower it is, the more the player will feel to be stuck in the mud.

Note: actually, right now, the current values are still better than in real life, so the players react faster & can change direction more easily