Animations are way too slow on BB10

import QtQuick 2.0

Rectangle {
    width: 768
    height: 1280
    color: "gray"

    Rectangle {
        id: inner
        width: parent.width
        height: parent.height
        x: -width
        color: "green"

        NumberAnimation {
            target: inner;
            property: "x";
            duration: 2000;
            from: -width
            to: 0;
            running: true
            loops: Animation.Infinite
        }
    }
}