Couple of other quick notes here:
Turn off “Realtime” when you are not using the viewport, if you have a blueprint open in front of the viewport, it will still be processing the scene in the background. Also make sure you do before walking away from your PC, it will save a lot of power. Just press CTRL+R to toggle it on/off.
Go into your Editor Preferences and check the box to “Use less CPU while in the background”, will lower the usage whenever UE4 is not the active window. When used in conjunction with realtime turned off, UE4 will not use up resources while it is not active. See attached to find setting. 