[SOLVED] The slowness is caused by the option for iTunes managing by folders (by artist, album, etc). Even though I'm not changing any ID3 info tags that affect the folder structure, this setting causes any change to take 5x longer than it should. My test on both a 2011 and 2014 Macbook pro took 2 minutes initially, un-checking this option brought the time down to 26 seconds for updating the grouping field on 30 tracks. ------------------------------ My 2011 Macbook Pro iTunes runs very slowly off my external drive, and a test on a similar spec 2014 Macbook Pro showed the same problem, actually the speeds were identical. Please help figure out how to improve the speed. My external drive is a WD 2TB USB 3.0 hard drive formatted to exFAT. Since my 2011's Macbook only has USB 2.0, I thought the 2014 Macbook with USB 3.0 capabilities would work much faster. When I copy files back and forward off the drive on the 2 machines, the 2014 is about 3x faster - showing the USB 3 difference. This also reflects when importing 30 songs (325MB) into iTunes on both machines (my Itunes library is on the machine harddrive in both cases, and iTunes is set to copy music to a folder on the external harddrive in both cases). So, on the 2014 machine, the import operation is about 3x faster (2 minutes vs 6 minutes). BUT, once the files are imported and working on both machines, the problem lies with very slow speeds to rename the ID3 tags (e.g. "grouping" or "year") , and on both machines the performance to rename 30 files takes 2min 2secs exactly. Why is the 2014 machine not 3x faster in this case? The apple support person said that in this example, for this type of operation, the external drive behaves like a USB 2.0 drive, so I lose the benefit on USB 3.0, but I don't understand why this operation is different to other tests I tried. He suggests I buy a lighting or firewire drive but those are much more expensive and I already own several USB 3.0 drives. Thanks for any insights, explanations and help!