Endnote X9 is frustratingly slow on my Mac running Mojave 10.14.3

I have a very large Endnote library with about 15,000 references, many with attached PDFs.  Completely independent of Word, the library is very slow.  When I search for an author by last name, it may take up to a minute to find her as the program successively searches for the paper, at each step incrementally closing in on the reference. 

I imagine that the slow speed is due in part to the size of the library but I think I need to have all of the references available because periodically, I will need some even if they are old and entered long ago. 

Any suggestions?

How many output styles, filters and connection files have you installed? If there are more than a couple hundred, it degrades endnote speed. 


I have fewer references than you do (3700 — most of them with PDF attachments), but I was experiencing the same types of issues. I contacted Clarivate and they mentioned that it was due to the changes in PDFKit in Mojave. In essence, PDFKit has some significant issues and since EndNote relies heavily on them, the performances drop to a crawl any time a PDF is involved. I managed to regain somewhat control of the app though by simply choosing NOT to display the PDFs on the sidebar at all. I have the sidebar set to “Right - Preview” and now I can again scroll, search etc without having the app beachball all the time. Now… that might not be the root cause of your issues on your Mac, but it might be worth investigating. Other factors can affect performances too. I made lots of changes to my library for instance. It all uploaded to the Clarivate server OK, but the other two Mac I use and that sync with my library became unusable (hanging, crashing…) as they were trying to download the changes. I had to copy my library on an external drive to manually replace the libraries on the other Mac to regain control there. Corentin

It’s quite a nightmare;  X9 is so slow on OS, it’s almost unusable!

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I have currently less than 1,000 references (with PDFs) brought over from another citation manager to give EndNote X9 another chance. The display of PDFs is not the only culprit for sluggish behavior. I have also the right pane set to “Right - Preview”. But switching from one reference to the next shows the beachball each time for about 3-4 seconds before the contents of the right pane is finally shown – on a current MacBook Pro with 16 GB of RAM running macOS 10.14.5. I do not know which database engine EndNote X9 is using, but this is something, which has to be improved with the highest priority.

I would like to confirm that updating Java fixed the spinning wheel for me. Before I had a spinning wheel whenenver I was dragging a reference to another group, now I can drag multiple references and it’s as quick as I expect it to be.

Java 8 Update 231

Endnote X9.3.1

Mac OS 10.12.6

Macbook Air End 2010

Credit goes to ScrippsOcean

And a note to Clarivate support: the fix was published by the above mentioned user back in May, yet no official update or even a note to update Java? Please improve support!

Dear Leanne,

I also had this problem of very slow Endnote X9.3.1 in Word for Mac 2016 and MacOS 10.15.1 Catalina.

Your advice to delete Output Styles was very helpful. I deleted all unnessecary output styles and Endnote now is so much faster. Thanks and best regards.

Wolfgang Widulle

University of Applied Sciences North Western Switzerland

Dear Herbert, 

As written below I deleted unnessecary connection files (more than hundred) and output styles. Endnote now works fine.

Wolfgang Widulle


Happy to see it worked for you, but the Java update did nothing for me.

Java 8u231

Endnote X9.3.2 (64bit)

MacOS Catalina 10.15.1

MacBook Pro 2016 2.9GHz quad-core, 16GB RAM

I had not tried that yet so I deleted all my connection files except PubMed and only kept about 10 output styles and it didn’t make a difference at all…

any update here? I have the same problem.