Since upgrading to 10.13, whenever I open large files, there's a bar that appears that says "Verifying [filename]". It usually takes around 10 seconds to clear before the video plays. I saw someone report the same problem for an older version of MacOS. I'm using a Mid 2011 imac, 8GB ram. I don't have filevault enabled. Will appreciate any advise on how to fix this please. Thank you!