We have observed that when moving certain nodes or ports, the diagram is slow to display the nodes/ports in their new positions. This seems to be dependent on when the node was added to the diagram.
Attached is a sample that adds 300 nodes to the diagram. The first node and the 300th node are next to each other. Try moving the first node and its ports around. Then try moving the 300th node and its ports around. The diagram struggles more to keep up when the first node is being moved, compared to when moving the 300th node.