You can remove all Google Apps like Google +, Maps, Youtube etc. except Play Store and Play Services.
You should not remove any Background Services like Tegrazone or something else. Otherwise Game Streaming or Tegrazone itself wonīt start.
A Tip: Remove Apps which appear in the App Drawer. Do not remove those which i mentioned earlier.
Then, you could try to remove services which stay in connection to Apps you removed earlier. Like E-Mail or Contacts.
Itīs somehow a hit and miss when you try to remove Apps. If you backed up everything with CWM, you could try it for yourself.
But if you remove those unnecassary Apps, the Nvidia Shield feels slightly faster when you are in the launcher.
And you get more storage space.