Canvas Group component is still calling "RandomSibling.Update()" even when "Canvas group" is disabled in the inspector.

Steps to reproduce:
1. Open attached project
2. Open "CanvasGroupMakesSetSiblingIndexReallySlow"
3. Select GameObject->Canvas
4. Go into play mode
5. Open Deep Profile and select BehaviourUpdate->RandomSibling.Update() (it should be using no more that 20% of CPU)
6. Now press Add Component->Canvas group (watch attached video)
7. RandomSibling.Update() increases to >90% in deep profiler
8. Now disable Canvas Group component in the Inspector
-RandomSibling.Update() still running >90%

Actual result: "Canvas Group" is still active even when it is disabled in the inspector.
Expected result: "Canvas Group" should become inactive once it was disabled.

Reproduced on 5.5.0b2, 5.4.0p4