Camera parenting to rigidbody

Hello, I have a rigidbody character controller (modified version from the wiki) for a fps, when I parent the camera to it I get a jerky motion, Setting the camera in a fixedUpdate loop fixed this (even though it isnt a rigidbody) as the camera's update wasnt syncing up with the rigidbody.

I later added a gun into the mix and made it follow the camera (without parenting anything) and found again a very jerky motion when i rotate the gun. I played around with how I update the gun's rotatation and tried parenting, unparenting and putting it in update, lateupdate and fixedUpdate. Putting it into the fixed update loop stopped the jerky motion again.

I am concerned about putting too many things into the fixedUpdate (especially things that have no rigidbody) as I am not too sure how it will affect performance on low fps (i have read the time manager docs and still not too sure)

Another question is, Am i the only person having trouble parenting non-rigidbody objects to rigidbodies?