High CPU usage when the view containing animation is not shown

Summary:
When a QQuickView whose source contains animation is not shown by,
1. being minimized,
2. or, being covered by any other windows,
the CPU usage of program is way too high.

Here's a very simple QML code including an animation:

import QtQuick 2.0

Rectangle {
 ColorAnimation on color { loops: Animation.Infinite; from: "white"; to: "black"; duration: 5000 }
}

I executed this qml code with next C++ code:

#include <QGuiApplication>
#include <QQuickView>

int main(int argc, char **argv) {
 QGuiApplication app(argc, argv);
 QQuickView view;
 view.setSource(QUrl::fromLocalFile("/path/to/qml"));
 view.setResizeMode(QQuickView::SizeRootObjectToView);
 view.resize(100, 100);
 view.show();
    return app.exec(&#41;;
}

As far as I'm seeing the scene, there's no problem and the CPU usage hits only about 5%.
However, the window is hidden by being minimized or covered other windows, the CPU usage reaches to about 90%.
If I recover the window shown normal, CPU usage also decreses to normal percentage(<5%).
Without animantions, the problem does not occur.