I've used Gaze and I've never seen any real performance issues.
we used it for halloweenfest 2015 and it had a very notable impact on the server since it was constantly running raycasts for 30+ players, smaller than that would be okay in most scenarios i guess, unless the server has a bunch of other constantly running functions as well.
anyways gaze fulfills the request here so its kindof a moot point. if there ends up being a problem with it performance-wise you can probably get someone to fix it pretty easily.