Memory consumption will explode when executing '/vis/scene/add/trajectories' for
drawing trajectories.

I suspect that G4VisManager::CheckModel() could cause memory leak.

  965  void G4VisManager::CheckModel () {
  966    G4VModel* pModel = fpSceneHandler->GetModel();
  967    if (!pModel) {  // provide a null model.
  968      pModel = &fVisManagerNullModel;
  969      fpSceneHandler -> SetModel (pModel);
  970    }
* 971    Ensure modeling parameters are right for this view...
* 972    fVisManagerModelingParameters
* 973      = *(fpSceneHandler -> CreateModelingParameters ());
* 974    pModel->SetModelingParameters (&fVisManagerModelingParameters);
  975  }

This method will be called at every time of drawing an object.
SceneHandler::CreateModelingParameters() will create new object of
G4ModelingParameters, but the object seems not to be well managed.