QT 3D NodeInstantiator performance issue - c++

Question

I want to visualize x,y,z points as cubic blocks. I use C++ for backend and qtquick/javascript for frontend. I have implemented QAbstractListModel in C++ side and exposing to qml (qtquick) with QQmlApplicationEngine rootContext. Data include only x,y,z points and color codes. Data have arround 500 thousand coordinate points. I'm trying to visualize this data with NodeInstantiator dynamically. But it takes too much time to create objects, and ram usage increasing rapidly to 5-6 GB. If I solve the performance issue, I will try to add border lines to blocks. And I don't know how to do it aswell.
OS: Windows 10
Ram: 8 GB max
GPU: Nvidia 970 GTX
QT Creator 7.0.0
Kit: Desktop Qt 5.15.2 MinGW 64 Bit
import QtQuick 2.15
import QtQuick.Window 2.15 as W
import QtQuick.Scene3D 2.15
import Qt3D.Core 2.15
import Qt3D.Render 2.15
import Qt3D.Extras 2.15
import Qt3D.Input 2.15
import QtQuick.Controls 2.5
Page {
Rectangle {
id: rect1
x:0
y:0
width: 100
height: 100
color: "red"
}
Scene3D {
id: scene3dId
anchors.top: rect1.bottom
anchors.bottom: parent.bottom
anchors.right: parent.right
anchors.left: parent.left
//anchors.fill: parent
aspects: ["input", "logic"]
Entity {
id: scene
property color baseColor
property real metalness
property real roughness
property real exposure
property real gamma
components: [
RenderSettings {
activeFrameGraph: ForwardRenderer {
camera: mainCamera
clearColor: "white"
gamma: scene.gamma
}
},
// Event Source will be set by the Qt3DQuickWindow
InputSettings { }
]
Camera {
id: mainCamera
position: Qt.vector3d(0, 0, 12)
viewCenter: Qt.vector3d(0, 0, 0)
fieldOfView: 60
exposure: scene.exposure
}
OrbitCameraController {
camera: mainCamera
linearSpeed: 1000
lookSpeed: 240
}
CuboidMesh{
id: cubeMesh
xExtent: 1
yExtent: 1
zExtent: 1
}
NodeInstantiator {
id: grid
model: BM
delegate:
Entity {
Transform {
id: transformId
translation: Qt.vector3d(model.X, model.Y, model.Z)
}
PhongMaterial {
id: cubeMaterial
ambient: model.Color
}
components: [transformId, cubeMesh, cubeMaterial]
}
}
}
}
}
An example of what I want to do