When you get more stuff on your iphone: like "music, video, photo, note, app, & games..." and anytime you syncing the iphone to add more stuff, the Itunes will take a lots of time to backup your iphone. So this tutorial will help you stop that problem.

1. Quit iTunes.
2. Open Finder => Applications => Utilities => open Terminal.app
3. Type (or copy & paste) following command:
defaults write com.apple.iTunes DeviceBackupsDisabled -bool true
4. Hit enter\Return
5. Open & run iTunes
6. Plug-in & connect iphone to computer for syncing. The backup process should be bypassed and skipped now. Now you'r good to syncing.

To re-enable or turn on the backup of iphone again.
1. Quit iTunes.
2. Open Finder => Applications => Utilities => open Terminal.app
3. Type (or copy & paste) following command:
defaults write com.apple.iTunes DeviceBackupsDisabled -bool false
4. Hit enter\Return
5. Open & run iTunes
6. Enjoy.