NOt sure in your version....
I am assuming you are in the ADVANCED Menu? You have to hold the menu button down for like 15 or 20 seconds for those menu items to appear, I know they moved from the setup menu in Ver 2 to the advanced in Ver. 3. Then scroll thru, it has bunch of settings (don't change any) until you see the HLF.
I know I have mine on HLF 2, and it only deviates maybe 1 degree. It bumps the response rate/feed rate faster on temperature changes.