has anyone else noticed this? when browsing in portrait the playbooknisnt as smooth and more sluggish. this is true with flash on or off,but is especially noticeable with flash support disabled. a smooth page in landscape (scrolling wise, smooth like ipad) suddenly becomes slow with low frame rate animations in portrait. even not browsing, on the main screen animartions are slow in portrait. contrast scrolling thru apps in the zoom out view in portrait vs landscspe. why is this? can the pb not keep up in portrait?