SceneGraph blocks GUI thread during rendering

GUI Thread Sync operation blocks the main thread for ~10msec for each frame on 60 FPS.

import QtQuick 2.12
import QtQuick.Window 2.12

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    Rectangle {
        anchors.centerIn: parent
        color: "red"
        width: 100; height: 100;


        RotationAnimator on rotation {
            loops: Animation.Infinite
            from: 0
            to: 360
            duration: 1000
        }
    }
}

qt.scenegraph.time.renderloop: [window 0x564f64539950][gui thread] polishAndSync: start, elapsed since last call: 16 ms
qt.scenegraph.time.renderloop: [window 0x564f64539950][render thread 0x564f64671730] syncAndRender: frame rendered in 16ms, sync=0, render=0, swap=16
qt.scenegraph.time.renderloop: [window 0x564f64539950][render thread 0x564f64671730] syncAndRender: start, elapsed since last call: 16 ms
qt.scenegraph.time.renderer: time in renderer: total=0ms, preprocess=0, updates=0, rendering=0
qt.scenegraph.time.renderloop: [window 0x564f64539950][gui thread] Frame prepared, polish=0 ms, lock=0 ms, blockedForSync=11 ms, animations=0 ms