My iPhoto always worked fine until recently. Now when I click on to a photo, it is blurry until I hit edit. I've deleted some photos. What a time waster this is. How can I resolve this issue?
This happens because your iCloud Photos are stored in original high resolution but the Mac keeps lower resolution previews to save space. If you want to change it, go to Photos, open Settings. Select iCloud and then select "Download Originals to this Mac". Be aware that the storage space required to keep all of your photos in original quality will increase over what you're using now.