`lookupviewservice` eats a lot memory
Solution 1:
I have the same problem. As I don't care about the Dictionary lookup service I disabled it. In System Preferences : Trackpad : Point & Click, I unchecked "Lookup & data detectors" and also "Force click and haptic feedback". Then I force quit the LookupViewService processes which Activity Monitor showed using a lot of Real Mem. Hope this helps.