Many people have been complaining – including myself – about the extremely long, tedious, and annoying backup procedure during the sync from your iPhone to your iTunes.
The syncing process is actually quick on it’s own – it’s the backup procedure that takes ages. That being said, here’s the extremely simple work around.
Simply click the X and the back up will stop. Your syncing will continue, it will just skip the back up process.
However, it’s important to back up your iPhone sometimes – so don’t skip it every time.