How to fix iPhone syncing delays with iOS in iTunes

I originally asked this over on the Apple Discussions website but after a week with no response, I’m guessing everyone there is as clueless as I am about fixing it, so I figured I would ask here.

iTunes on 2011 iMac with MacOS 10.13.6 and iPhone 12 with iOS 17.3.1

I connect the iPhone to the iMac via USB cable and click on “Sync” in iTunes. The process then sits in the “Preparing to sync” step for several minutes (at least 5) before actually syncing. It did NOT do this with iOS 16.7.2, but started with iOS 17. In the amount of time it takes for the iPhone to actually begin syncing, I can do the following: Connect, sync, and back up both my iPad Mini 6 running iPadOS 16.7.2 and my iPad Mini 5 running iPadOS 14.4.2 to iTunes AND then back both of them up using iMazing 3.

Anyone have an idea how to get back to the faster syncing of iOS 16?