In Windows Task Manager - what is AppleMobileDevice, system user? It is running 55% or more and makes the cpu usage at 55-100%
I found an Apple discussion thread about this issue:
The thread suggests that the problem was introduced by an iTunes update. The suggested fix is uninstalling and reinstalling iTunes, following a specific set of steps. Here's the link from Apple with the uninstallation/reinstallation steps:
I do not have Windows, and I have not verified the problem or the solution.