when returning to home screen thee are times that tiles go blank and take time to load. u scroll down and u will see tiles and icons after 1 or 2 seconds. I have noticed that this happens to all my apps pinned on the start screen which are installed in SD card. coz apps like watsapp and OneNote don't take time to load the tile while returning to home screen. does anybody else get the problem with their apps on SD card. i guess even if you suffer from any kind of minor lag on 8.1 that's due to SD card which loads apps on start screen all the time.