IAccessibleHandler: instead of checking if a winEvent is for a native UIA window in winEventCallback, check this in OrderedWinEventLimiter.flushEvents. Also cache the answer to whether its a UIA window or not, for the period of the flush. This should massivly cut down the amount of times NVDA neds to call UIAIsServerSideProvider(window), which may speed things up when using UIA.