Having problems with iTunes maxing out your CPU to 100% every time you plugin or sync a phone or even in some cases just start your PC. Processes like these may be shown taking up almost all of the available CPU
As it would turn out Kaspersky 2015/2016 is completely incompatible with iTunes on Windows 10 (and there’s various combinations of incompatibilities on the older Windows OSes). So the painful solution is uninstall Kaspersky and restart (uninstall it completely don’t just disable it temporarily as it leaves half of it’s services running in the new version and you can’t actually disable it). Open iTunes and confirm your CPU is back to normal (as I did – it had gone from 100% constant to now 1-3% while doing a sync).
This is very annoying hopefully Kaspersky fixes it but in the meantime it’s easier to use one of the others or just use Windows defender until there’s a patch for Kaspersky.