Is there a way to turn off automatic updating in an app, and to let me call it when I want? It causes me some inconvenience to have to do everything from within simpleUpdate.
I think of the jme part of my game as a graphics module, not my main module.
No, you shouldn’t do that. Try doing this differently either by using callables or by having some synchronized state class where you move the data from the other part of the app and the jme3 update loop reads it.
The updating needs to be synchronized with the rendering 1:1. It won’t harm performance usually, not unless you make changes to large parts of the scene graph.
You can change the scene graph asynchronously from another thread by using Callables like normen said.
Note that you can also build portions of the scene graph from other threads as long as you only attach them to the scene from the jme thread… and then leave them alone from the other threads. 