Maybe I'm doing something incorrect cause I can't get the triangles to be drawn/updated when assigning controller, applying, removing and then calling build. Here's what I do:
int vertexCount = object.getMesh().getUniqueVertexCount();

JpctVertexController2 controller = new JpctVertexController2();
object.getMesh().setVertexController(controller, true);

JpctMeshData initData = new JpctMeshData(vertexCount);
controller.updateMeshData(initData.vertexData, initData.normalData);
object.getMesh().applyVertexController();
object.touch();
object.getMesh().removeVertexController();

object.build();
world.addObject(object);

where JpctMeshData is just initialized as:
public JpctMeshData(int size) {
        vertexData = new SimpleVector[size];
        normalData = new SimpleVector[size];

        for(int i = 0; i < vertexData.length; i++) {
            vertexData[i] = new SimpleVector();
            normalData[i] = new SimpleVector(0, -1, 0);
        }
    }

and controller.updateMeshData():
public synchronized void updateMeshData(SimpleVector[] meshData, SimpleVector[] normalData) {
        SimpleVector[] destinationMesh = getDestinationMesh();
        SimpleVector[] destinationNormals = getDestinationNormals();
        System.arraycopy(meshData, 0, destinationMesh, 0, meshData.length);
        System.arraycopy(normalData, 0, destinationNormals, 0, normalData.length);
    }

Had the same problem earlier. That's why I had to keep the controller but only update it the first time and then continue by only updating the attributes..

You might want to try to apply the controller just once, remove it and call build afterwards. Just to see if that changes something. It shouldn't, but just to rule that out...

In both cases, I'm still using vertex attributes, one static for drawing the wireframe based on barycentric coordinates and one dynamic for the coloring of the vertcies. The thing that differs is how the position of the vertices are updated.

In the vertex attribute case, I couldn't get the position update to work if I didn't do one initializing update using a vertex controller. But after that first update, it worked by only updating the position via the attribute.

I'm only calling build() on the Object3D

Now I got the profiling to work. Updating the vertex attributes instead of the vertex controller is indeed faster, however, when it comes to the rendering, updating the vertex attributes takes longer time in draw() and renderScene(). Don't know if these screencaps of the top down charts can give you any clues, but here they are: https://www.dropbox.com/sh/809ag9of4esvlig/AAB3OcqPMtVRw1fSQ0uuZCYra?dl=0

*_vert_attr = changing vertex position via vertex attribute
*_vert_controller = changing via vertex controller

From what I can see, the function fillAttributes() differs quite alot, especially the get() from ArrayList in the vertex attribute case.

Since I'm using the "position" attribute, is there any chance that stuff gets written/updated twice when it doesn't have to? I mean, the position attribute is written anyway right? Or is it some other magic going on under the hood?

Thanks alot for the support!

Thanks, I hope you see a cool game this year.
I need something like object.clearRotation and preferably object.clearTranslation to apply to sourceMesh.clearRotation and sourceMesh.clearTranslation.

Good luck