"QuickLookUIService" Using Significant Energy

I had the same problem. Here's a suggestion that worked for me, it involves creating a daemon that will kill the service QuickLookUIService every 5600 seconds (you can tune this setting). Whole answer here with the daemon code is here: https://discussions.apple.com/thread/8506070

The one that I had to Force Quit everytime was QuickLookUIService (Spotlight). I'm running Mojave 10.14.6 on a Mid 2012 Macbook Pro 15' non-retina.

In a nutshell, this service is not responding using significant energy and avoiding switching to the integrated graphics, draining your battery until you kill it.