That kind of depends on how your doing your movements.
In my case they are given a set amount of time to reach their destination before their told to move again.
But that's not really what I was worried about, I was getting lag when I created a new instance, and my theory was that that creating an obstacle map was causing the lag.
Actually what I've found is that using the "Solid" attribute for the map was really what was slowing it down.
Just adding the object as an obstacle works much, much better.