Endnote X8.1 Slow on MacOS 10.13 High Sierra

I hadn’t used EndNote in about a month, so I’m not sure what is causing this. Since I last used EndNote I updated to MacOS 10.13. When I opened EndNote this morning it prompted me to update to 8.1, and I did so. After that I proceeded to conduct searchers and import references from PubMed, PsychINFO, and Web of Science. I noticed it was running slowly, but it was fine until I began working more heavily in EndNote. I was trying to go through the combined searches and delete duplicates after sorting by title. Every time I would click on a reference that was unread it was slow down and show the spinning color wheel which is associated with freezes on the Mac. I selected all and marked as read thinking that might fix it. As I selected multiple article to weed out, it continued to show me the spinning color wheel every few seconds. It was maddeningly slow! I thought maybe I had too many references in my library, so I created a copy and deleted all older references. I was still seeing the same issues. Eventually, I had to restart and boot into Windows to do my work. Once I booted into Windows, Endnote 8.1 was working great- very responsive. I shouldn’t have to boot into Windows to use EndNote. This is unacceptable.

What is going on with the Mac version? Why is it so slow? Please fix!!!