Without write libraries it's a dead product. What surprises me is how fast HEIF files are on my iPhone 7 Plus (instantaneous browsing through photo library on

Without write libraries it's a dead product. What surprises me is how fast HEIF files are on my iPhone 7 Plus (instantaneous browsing through photo library on iPhone. No different to JPEGs), yet how sluggish it is on my 2017 MBP 13". Select a .heic on your Mac and spacebar-preview it. Then select another one in the same folder and you'll see it takes a good few seconds (depending on size of image).