Hope this can help.
First off, if you prefer to no back up your iphone to your computer I would suggest backing it up to icloud. you can do this by next time you plug in your iphone in itunes,
go to your device on the sidebar -->summary(its at the top) --> then on the summary page go to Backups and select "iCloud" ... or at least make sure the option that says "This Computer" [A full backup of this iphone will be stores on your computer ] is unchecked.
Doing this, it will stop making backups on your computer and make your backups to apple servers
Next just as Powerbook 1818 said you could go to Itunes-> Preferences -> Devices -> and then check the option that says " Prevent ipods, iphones, and ipads from syncing automatically
This will prevent from itunes from automatically syncying your device right away when plugging it in.
Lastly, plug your iphone into itunes,
go to devices -> your iphone -> summary -> scroll down and find the options ( its the box right under the Backup box from earlier in this post)
Then what i recommend is that you have the following UNchecked
- "Automatically sync when iphone is connected"
- Sync with this iphone over wifi"
-Sync only checked songs and videos( I dont think you have to do this, but I have it checked for myself
Then check:
-Mannually manage music and videos
From what I understand this will prevent it from sync and backing up to your computer, when I first plugged in my iphone it sync some other things (browsing data and a few other small things) but it didnt take anything longer than about 10 seconds max
I hope this helps!
Nic