main.qml

import QtQuick 2.12
import QtQuick.Window 2.12

Window {
    visible: true
//    width: 1920
//    height: 1080

    property int counts: 0

//    Text {
//        text: counts
//        color: "white"
//    }

    SimpleScene {
        //anchors.fill: parent
        width: 1280
        height: 720
        visible: false // this does not stop internal processing, needs comment-out all to stop processing.
    }

//    ShadowScene {
//        //anchors.fill: parent
//        width: 1280
//        height: 720
//        visible: false // this does not stop internal processing
//    }

    Text {
        id: fps
        font.pixelSize: 100
    }

    onFrameSwapped: counts++

    Timer {
        running: true
        repeat: true
        interval: 1000
        onTriggered: {
            fps.text = counts
            counts = 0
        }
    }
}