Here you are a possible workaround by overriding the RadRating's _mouseOut method:

<telerik:RadRating ID="RR1" runat="server" RenderMode="Lightweight" Precision="Item">
    <Items>
        <telerik:RadRatingItem Value="0" />
        <telerik:RadRatingItem Value="1" />
        <telerik:RadRatingItem Value="2" />
        <telerik:RadRatingItem Value="3" />
        <telerik:RadRatingItem Value="4" />
    </Items>
</telerik:RadRating>

<script>
    Telerik.Web.UI.RadRating.prototype._mouseOut = function (e, mouseMove) {
        var isMouseOverUl = $telerik.isMouseOverElementEx(this._ulWrapper, e);
        if (isMouseOverUl) {
            // Clear the reference here as the mouseOver event is raised after the mouseMove with reference to the old hovered item. Thus the code for
            // mouseMove is executed for the old hovered item with mouse coordinates relative to the new hovered item leading to blinking effect.
            if (!mouseMove && $T.RatingPrecision.Item != this._precision)
                this._hoveredItem = null;

            $telerik.cancelRawEvent(e);
        }

        this._attachDocumentHandlers(false);
        this._createPartElements(false);
        this._storeStartCoords(false);
        this._spanSize = null;
        this._hoveredItem = null;

        this._clearOverState();
        if (this._clearSelectedStateOnHover)
            this._synchronizeUIWithValue(this._value);
    };
</script>