Currently adding additional shapes to the diagram can cause the layout manager to re-adjust the position of current visual shapes(shapedefaults: {visual}). It would be nice to have an additional event after all dataitems has been retrieved, currently the databound is executed for every row.
The dataBound event of the diagram is actually fired after all items in it are bound to data, hence you should be able to utilize it. You can test that in the following demo: http://demos.telerik.com/kendo-ui/diagram/events