Long Sync times...... Solved!!!

Question

Over the past 2 months I have been moving my nearly 4TB iTunes Library from Win 7 64bit to my brand new Mac Mini with Lion. Like many, I made the assumption that because iTunes was an Apple product it would run at its best on an Apple product. So far, the jury is still out on this one.
During the process of moving I discovered 2 bugs with iTunes. The first one was to do with consolidating an iTunes Library in an area greater than 4TB (I have reported this using the usual channels). The second one isn't quite so "rare" and may benefit others which is why I decided to open this thread.
In my house there are 3 Apple TV's (Gen 1), 2 iPod Touch's, 1 iPad and 4 iTunes users (with corresponding libraries of various sizes). In the center is what we laughlingly call our iTunes Server which now resides on a Mac Mini (2.7GHz 4G). It took many attempts to move our primary library from Windows to Mac (I will try to document all the problems on another occasion) but when I eventually got it working I noticed that sync times on any device attached to the Mac Mini library would take a minimum of 20 minutes no matter how small the sync should have been. In all cases the first 15 to 20 minutes consisted of the Mac Mini running at around 100% CPU without actually achieving much and then suddenly the CPU would reduce down to lower levels and the sync would complete as normal. Initially I thought iTunes was in a loop but eventually decided to let it run just to see what would happen....and sure enough it eventually completed normally.
Rather than go through all the different things that I tried to sort this out I will simply point out what I think is a bug in the Mac version of the product (it works OK in the Windows version). We have a family photo library with over 80000 photos in it. When syncing any device with photos from this library I used to select the root directory of the library and then simply select "selected folders" within that library inside the iTunes Photos Tab. This method had worked ok for us for at least 3 years in the old Windows environment. In the Mac environment however iTunes appears to need to cycle through the whole photo library EVERY TIME before it starts to actually sync. If instead I simply picked one folder with say 2000 photos in it, it would start syncing instantly without any delay. I can happily reproduce this problem whenever I want to.
So if you have long sync times ONE option is to check how you are accessing your photo library.   

Answer 1

I'm experiencing this problem too. It goes through syncing Contacts, Calendars, etc. and then it say Syncing iPhone and hangs. CPU usage for iTunes goes from 7-10 to 103 and stays pegged. I have discovered that if I go to the "Advanced" section of the "Info" tab in iTunes and select "Replace information on this iPhone" that it will sync successfully, but only for that sync and the next sync will again hang. This trick seems to work whether I select all the "replace" options (Contacts, Calendars, Bookmarks, Notes, and Mail Accounts) or just one (I tried with just Notes selected).
I haven't tried the Restore option yet.