Cannot render dozens of MeshInstance3Ds asynchronously (just render all at once)

[wxzen]

Godot Version

4.2.1

Question

I have encountered an issue related to rendering. Specifically, I am trying to add MeshInstance3D nodes to the scene and render them one by one as they are added, but instead, all nodes are rendered at once after they have all been added.
Is there a way to achieve sequential rendering of MeshInstance3D nodes in Godot Engine 4.2? I would like to see each node being rendered as it is added to the scene, rather than all at once.
I have read through the Godot documentation and searched for similar issues online, but have not found a satisfactory solution. Any help or advice would be greatly appreciated.

Thank you in advance for your time and assistance.

void *GodotPrepareRendererResources::prepareInMainThread( Cesium3DTilesSelection::Tile &tile,
                                                          void *pLoadThreadResult_ )
{
    ...

    std::vector<MeshInstance3D *> meshInstances;
    meshInstances.reserve( meshSize );
    for ( int i = 0; i < meshSize; ++i )
    {
        MeshInstance3D *meshInstance = memnew( MeshInstance3D );
        meshInstance->set_name( godot::String( name.c_str() ) );
        meshInstance->set_mesh( meshes[i] );
        // cesium coordinate axis X is not align godot's, need rotate.
        Quaternion qua( Vector3( 1, 0, 0 ), static_cast<real_t>( -Math_PI / 2 ) );
        Transform3D trans;
        trans.set_basis( qua );
        meshInstance->set_transform( trans );
        meshInstance->set_visible( false );
        this->_tileset.add_child( meshInstance );
        // this->_tileset.call_deferred("add_child", meshInstance);
        meshInstances.push_back( meshInstance );
    }

    ...
 }

void Cesium3DTileset::_process( double delta )
{
   ...

    for ( auto pTile : updateResult.tilesFadingOut )
    {
        if ( pTile->getState() != TileLoadState::Done )
        {
            continue;
        }

        const Cesium3DTilesSelection::TileContent &content = pTile->getContent();
        const Cesium3DTilesSelection::TileRenderContent *pRenderContent =
            content.getRenderContent();
        if ( pRenderContent )
        {
            CesiumGltfNode *pCesiumGltfNode =
                static_cast<CesiumGltfNode *>( pRenderContent->getRenderResources() );
            if ( pCesiumGltfNode )
            {
                for ( MeshInstance3D *instance3d : pCesiumGltfNode->pNodes )
                {
                    // instance3d->set_visible( false );
                    instance3d->call_deferred( "set_visible", false );
                }
            }
        }
    }

    for ( auto pTile : updateResult.tilesToRenderThisFrame )
    {
        if ( pTile->getState() != TileLoadState::Done )
        {
            continue;
        }
        const Cesium3DTilesSelection::TileContent &content = pTile->getContent();
        const Cesium3DTilesSelection::TileRenderContent *pRenderContent =
            content.getRenderContent();
        if ( pRenderContent )
        {
            CesiumGltfNode *pCesiumGltfNode =
                static_cast<CesiumGltfNode *>( pRenderContent->getRenderResources() );
            if ( pCesiumGltfNode )
            {
                for ( MeshInstance3D *instance3d : pCesiumGltfNode->pNodes )
                {
                    // instance3d->set_visible( true );
                    instance3d->call_deferred( "set_visible", true );
                }
            }
        }
    }
}